Patent Publication Number: US-8535207-B2

Title: Bi-directional tensioning apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of and claims priority under 35 U.S.C. §120 to U.S. application Ser. No. 12/724,193, filed on Mar. 15, 2010, the entire contents of which is incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     Elastic bands, such as bungee cords, are commonly used to provide tension in tie-down equipment, exercise equipment, physical rehabilitation equipment, portable scaffolding, and the like. However, bungee cords with hooks pose considerable danger to the user. Typically, the user hooks one end of the bungee cord to the equipment, pulls the bungee cord to tighten it, and hooks the other end of the bungee cord to the equipment. If any of the metal hooks come loose during this process, the free metal hook can act like a bullet and hit the user with considerable force to severely bruise the skin or to damage to the user&#39;s eye. 
     Further, any device that attaches to the elastic body of the bungee cord runs the risk of damaging the elastic member by abrasion, shearing, and tearing, thereby creating increased risk to the user. 
     Accordingly, there is a need for an elastic member and apparatus for securing the elastic member that does not pose physical danger to the user or damages the elastic member. 
     SUMMARY OF THE INVENTION 
     The present invention provides a bi-directional tensioning apparatus that includes, for example, an elongate resilient member, a support member, a first guide member, and a second guide member. The bi-directional tensioning apparatus is able to hold the second guide member in an equilibrium position intermediate the base end and the remote end of the support member. When a force is applied to the second guide member, the bi-directional tensioning apparatus exerts an opposing force. 
     The unique structure of the bi-directional tensioning apparatus preserves the elongate resilient member strength and integrity by not squeezing, bending, or constricting the elongate resilient member during use. Therefore, no weak spots in the elongate resilient member are created by tearing, shearing, and abrading. The elongate resilient member includes, for example, enlargements, which are captured by the support member, the first guide member, and the second guide member to provide bi-directional tension. 
     The bi-directional tensioning apparatus as described herein, find applications, for example, tie-down equipment, exercise equipment, physical rehabilitation equipment, portable scaffolding, and the like. 
     The present invention provides a bi-directional tensioning apparatus. The bi-directional tensioning apparatus includes: 
     one or more elongate resilient members each having a base end and a remote end,
         wherein the one or more elongate resilient members each include a first elastic material with a first enlargement at the base end and one or more spaced-apart enlargements along the length of each of the one or more elongate resilient members;       

     one or more support members each having a base end and a remote end,
         wherein the one or more support members each include one or more optional first cavities at each remote end for receiving and holding the one or more elongate resilient members;       

     one or more first guide members each having a base end and a remote end,
         wherein the one or more first guide members is each independently connected at or proximate to the base end of each of the one or more support members and extending generally perpendicular thereto,   wherein the one or more first guide members each independently include a first hole extending through the one or more first guide members and generally parallel to the one or more support members;       

     one or more optional couplers for independently securing one of the one or more spaced-apart enlargements, and 
     one or more optional second guide members each having a base end and a remote end,
         wherein each of the one or more optional second guide members is movably mounted on each of the one or more support members between the one or more first guide members and the remote end of each of the one or more support members and extending generally perpendicular thereto,   wherein the one or more optional second guide members each independently include a first snap-fit device on the base end and an optional second snap-fit device on the remote end for independently receiving one of the one or more support members,   wherein the one or more optional second guide members each include one or more connectors for independently securing one of the one or more spaced-apart enlargements,   wherein the one or more connectors each extend through each of the one or more optional second guide members and generally parallel to the one or more support members,   wherein the one or more optional second guide members each independently rest at a point of equilibrium intermediate the base end and the remote end of each of the one or more support members.   In one embodiment, if one support member and one first guide member are present, then the one first guide member penetrates opposite sidewalls of the support member or forms a third snap-fit device with the support member to form an interconnecting frame. In one embodiment, if one support member and two first guide members are present, then the two first guide members are each independently connected to opposite sidewalls of support member or form a fourth snap-fit device with the support member to form an interconnecting frame. In one embodiment, if one support member and two second guide members are present, then each of the one or more first snap-fit devices accepts the one support member.       

     The present invention provides a bi-directional tensioning apparatus. The bi-directional tensioning apparatus includes: 
     one or more elongate resilient members each having a base end and a remote end,
         wherein the one or more elongate resilient members each comprise a first elastic material with a first enlargement at the base end and one or more spaced-apart enlargements along the length of each of the one or more elongate resilient members;       

     one or more support members each having a base end and a remote end,
         wherein the one or more support members each comprise one or more optional first cavities at each remote end for receiving and holding the one or more elongate resilient members;       

     one or more first guide members each having a base end and a remote end,
         wherein the one or more first guide members is each independently connected at or proximate to the base end of each of the one or more support members and extending generally perpendicular thereto,   wherein the one or more first guide members each independently comprise a first hole extending through the one or more first guide members and generally parallel to the one or more support members; and       

     one or more second guide members each having a base end and a remote end,
         wherein each of the one or more second guide members is movably mounted on each of the one or more support members between the one or more first guide members and the remote end of each of the one or more support members and extending generally perpendicular thereto,   wherein the one or more second guide members each independently comprise a first snap-fit device on the base end and an optional second snap-fit device on the remote end for independently receiving one of the one or more support members,   wherein the one or more second guide members each comprise one or more connectors for independently securing one of the one or more spaced-apart enlargements,   wherein the one or more connectors each extend through each of the one or more second guide members and generally parallel to the one or more support members,   wherein the one or more second guide members each independently rest at a point of equilibrium intermediate the base end and the remote end of each of the one or more support members.       

     In one embodiment, the first enlargement at the base end has a thickness greater than or equal to the thicknesses of each the one or more spaced-apart enlargements. In another embodiment, the first enlargement at the base end, the one or more spaced-apart enlargements, or a combination thereof, each independently include the first elastic material, a knot of elastic material, a wooden material, a metal material, a plastic material, a second elastic material, or a combination thereof. 
     In yet another embodiment, each of the one or more optional first cavities has a width less than or equal to the thickness of the one or more spaced-apart enlargements and greater than or equal to the thickness of the one or more elongate resilient members. 
     In one embodiment, the diameter of the first hole is less than or equal to the thickness of the first enlargement and greater than or equal to the thickness of the one or more spaced-apart enlargements. In another embodiment, the one or more connectors each include one or more keyhole connectors, one or more adjustable clamps, one or more strictures, one or more slots, one or more grommets, one or more captures, or combinations thereof. In yet another embodiment, the one or more keyhole connectors each include a first hole, an optional second cavity, and a second hole, wherein the first hole intersects the second hole for passage of the one or more elongate resilient members from the first hole to the second hole, wherein if the optional second cavity is present, the first hole intersects the optional second cavity having an intersection with the second hole such the one or more elongate resilient members may pass from the first hole through the optional second cavity to the second hole. 
     In one embodiment, the diameter of the first hole in each of the one or more keyhole connectors is greater than or equal to the thickness of the one or more spaced-apart enlargements. In another embodiment, the diameter of a second hole in each of the one or more keyhole connectors is less than or equal to the thickness of the one or more spaced-apart enlargements. In yet another embodiment, the width of a key in each of the one or more keyhole connectors is less than or equal to the thickness of the one or more spaced-apart enlargements and greater than or equal to the thickness of the one or more elongate resilient members. 
     In one embodiment, the one or more optional second guide members each independently slides along each of the one or more support members. In another embodiment, the one or more support members each independently include one or more couplers located at or proximate each base end of each of the one or more support members. In yet another embodiment, the one or more couplers are independently connected to the one or more first guide members by one or more snap buttons disposed within the base end of each of the one or more first guide members. 
     In one embodiment, one support member, one first guide member, and one second guide member are present or wherein one support member, two first guide members, and two second guide members are present, or wherein two support members, one first guide member, and one second guide member are present. 
     In one embodiment, each of the one or more support members is a rigid support member. In another embodiment, each of the one or more support members is a non-rigid support member. In yet another embodiment, each of the one or more support members is independently a rigid support member or a non-rigid support member. 
     In one embodiment, each of the one or more first guide members is a rigid first guide member. In another embodiment, each of the one or more first guide members is a non-rigid first guide member. In yet another embodiment, each of the one or more first guide members is independently a rigid first guide member or a non-rigid first guide member. 
     In one embodiment, each of the one or more optional second guide members is a rigid second guide member. In another embodiment, each of the one or more optional second guide members is a non-rigid second guide member. In yet another embodiment, each of the one or more optional second guide members is independently a rigid second guide member or a non-rigid second guide member. 
     The present invention provides a bi-directional tensioning apparatus. The bi-directional tensioning apparatus includes: 
     one or more elongate resilient members each having a base end and a remote end,
         wherein the one or more elongate resilient members each include a first elastic material with a first enlargement at the base end and one or more spaced-apart enlargements along the length of each of the one or more elongate resilient members,   wherein the first enlargement at the base end has a thickness greater than or equal to the thicknesses of each the one or more spaced-apart enlargements,   wherein the first enlargement at the base end, the one or more spaced-apart enlargements, or a combination thereof, each include the first elastic material;       

     two support members each having a base end and a remote end,
         wherein the two support members each include a first cavity at each remote end for receiving and holding the one or more elongate resilient members,   wherein each first cavity has a width less than or equal to the thickness of the one or more spaced-apart enlargements and greater than or equal to the thickness of the one or more elongate resilient members;       

     a first guide member having a base end and a remote end,
         wherein the first guide member is connected at or proximate to the base end of each of the two support members and extending generally perpendicular thereto,
           wherein the first guide member includes a first hole extending through the first guide member and generally parallel to the two support members,   wherein the diameter of the first hole is less than or equal to the thickness of the first enlargement and greater than or equal to the thickness of the one or more spaced-apart enlargements; and   
               

     a second guide member having a base end and a remote end,
         wherein the second guide member is movably mounted on the two support members between the first guide member and the remote end of each of the two support members and extending generally perpendicular thereto,   wherein the second guide member rests at a point of equilibrium intermediate the base end and the remote ends of the two support members,   wherein the second guide member includes a first snap-fit device on the base end and a second snap-fit device on the remote end for independently receiving the two support members,   wherein the second guide member includes one or more keyhole connectors for independently securing one of the one or more spaced-apart enlargements,   wherein the one or more keyhole connectors each extend through the second guide member and generally parallel to the two support members,   wherein the one or more keyhole connectors each include a first hole, a cavity, and a second hole,   wherein the first hole intersects the second cavity having an intersection with the second hole such the one or more elongate resilient members may pass from the first hole through the second cavity to the second hole,   wherein the diameter of the first hole in each of the one or more keyhole connectors is greater than or equal to the thickness of the one or more spaced-apart enlargements,   wherein the diameter of a second hole in each of the one or more keyhole connectors is less than or equal to the thickness of the one or more spaced-apart enlargements,   wherein the width of a second cavity in each of the one or more keyhole connectors is less than or equal to the thickness of the one or more spaced-apart enlargements and greater than or equal to the thickness of the one or more elongate resilient members.       

     In one embodiment, the second guide member slides along each of the two support members. In another embodiment, the elastic material is flexible and stretchable. In yet another embodiment, the two support members each independently include one or more couplers located at or proximate each base end of each of the two support members. 
     In one embodiment, the one or more couplers are independently connected to the first guide member by one or more snap buttons disposed within the base end of the first guide member. 
     In one embodiment, each of the one or more support members is a rigid support member. 
     In another embodiment, each of the one or more support members is a non-rigid support member. In yet another embodiment, each of the one or more support members is independently a rigid support member or a non-rigid support member. 
     In one embodiment, each of the one or more first guide members is a rigid first guide member. In another embodiment, each of the one or more first guide members is a non-rigid first guide member. In yet another embodiment, each of the one or more first guide members is independently a rigid first guide member or a non-rigid first guide member. 
     In one embodiment, each of the one or more optional second guide members is a rigid second guide member. In another embodiment, each of the one or more optional second guide members is a non-rigid second guide member. In yet another embodiment, each of the one or more optional second guide members is independently a rigid second guide member or a non-rigid second guide member. 
     The present invention provides a method for using a bi-directional tensioning apparatus. The method includes: 
     providing a bi-directional tensioning apparatus including: 
     one or more elongate resilient members each having a base end and a remote end,
         wherein the one or more elongate resilient members each include a first elastic material with a first enlargement at the base end and one or more spaced-apart enlargements along the length of each of the one or more elongate resilient members;       

     one or more support members each having a base end and a remote end,
         wherein the one or more support members each include one or more optional first cavities at each remote end for receiving and holding the one or more elongate resilient members;       

     one or more first guide members each having a base end and a remote end,
         wherein the one or more first guide members is each independently connected at or proximate to the base end of each of the one or more support members and extending generally perpendicular thereto,   wherein the one or more first guide members each independently include a first hole extending through the one or more first guide members and generally parallel to the one or more support members;       

     one or more optional couplers for independently securing one of the one or more spaced-apart enlargements, and 
     one or more optional second guide members each having a base end and a remote end,
         wherein each of the one or more optional second guide members is movably mounted on each of the one or more support members between the one or more first guide members and the remote end of each of the one or more support members and extending generally perpendicular thereto,   wherein the one or more optional second guide members each independently include a first snap-fit device on the base end and an optional second snap-fit device on the remote end for independently receiving one of the one or more support members,   wherein the one or more optional second guide members each include one or more connectors for independently securing one of the one or more spaced-apart enlargements,   wherein the one or more connectors each extend through each of the one or more optional second guide members and generally parallel to the one or more support members;       

     displacing the one or more optional couplers or the one or more optional second guide members; and 
     engaging the one or more spaced-apart enlargements in the one or more optional couplers or the one or more connectors to provide that the one or more optional couplers or the one or more optional second guide members each independently rest at a point of equilibrium intermediate the base end and the remote end of each of the one or more support members. 
     The present invention provides a bi-directional tensioning apparatus. The bi-directional tensioning apparatus includes: 
     one or more elongate resilient members each having a base end and a remote end,
         wherein the one or more elongate resilient members each comprise a first elastic material with a first enlargement at the base end and one or more spaced-apart enlargements along the length of each of the one or more elongate resilient members;       

     one or more support members each having a base end and a remote end,
         wherein the one or more support members each comprise one or more optional first cavities at each remote end for receiving and holding the one or more elongate resilient members;       

     one or more first guide members each having a base end and a remote end,
         wherein the one or more first guide members is each independently connected at or proximate to the base end of each of the one or more support members and extending generally perpendicular thereto,   wherein the one or more first guide members each independently comprise a first hole extending through the one or more first guide members and generally parallel to the one or more support members; and       

     one or more couplers for independently securing one of the one or more spaced-apart enlargements. 
     The present invention provides a method for using a bi-directional tensioning apparatus. The method includes: 
     providing a bi-directional tensioning apparatus including: 
     one or more elongate resilient members each having a base end and a remote end,
         wherein the one or more elongate resilient members each comprise a first elastic material with a first enlargement at the base end and one or more spaced-apart enlargements along the length of each of the one or more elongate resilient members;       

     one or more support members each having a base end and a remote end,
         wherein the one or more support members each comprise one or more optional first cavities at each remote end for receiving and holding the one or more elongate resilient members;       

     one or more first guide members each having a base end and a remote end,
         wherein the one or more first guide members is each independently connected at or proximate to the base end of each of the one or more support members and extending generally perpendicular thereto,   wherein the one or more first guide members each independently comprise a first hole extending through the one or more first guide members and generally parallel to the one or more support members; and       

     one or more couplers for independently securing one of the one or more spaced-apart enlargements. 
     displacing the one or more couplers; and 
     engaging the one or more spaced-apart enlargements in the one or more couplers to provide that the one or more couplers rests at a point of equilibrium intermediate the base end and the remote end of each of one or more elongate resilient members. 
     The present invention provides a bi-directional tensioning apparatus. The bi-directional tensioning apparatus includes: 
     two elongate resilient members each having a base end and a remote end,
         wherein the two elongate resilient members each comprise a first elastic material with a first enlargement at the base end and one or more spaced-apart enlargements along the length of each of the two elongate resilient members;       

     two supporting frames each having a first support member, a second support member coupled perpendicular to the first support member, and a third support member couple perpendicular to the second support member and extending from the second support member in the same direction as the first support member,
         wherein the first support member and the third support member each comprise a cavity for receiving and holding one of the two elongate resilient members;       

     one or more guide members each having a base end and a remote end,
         wherein the one or more guide members is each independently connected to each of the two supporting frames and extending generally perpendicular thereto,   wherein the two first support members each independently comprise a first hole extending through each of the two first support members and generally parallel to the each of the two second support members; and       

     one cross member having a base end and a remote end,
         wherein the one cross member includes two connectors for independently securing one of the one or more spaced-apart enlargements along the length of each of the two elongate resilient members,   wherein the one or more connectors each extend through each of the one cross member and generally parallel to the one or more guide members and perpendicular to the two supporting frames,   wherein the one cross member rests at a point of equilibrium intermediate the base end and the remote end of each of two elongate resilient members.       

     The present invention provides a method for using a bi-directional tensioning apparatus. The method includes:
         providing a bi-directional tensioning apparatus including:   two elongate resilient members each having a base end and a remote end,
           wherein the two elongate resilient members each comprise a first elastic material with a first enlargement at the base end and one or more spaced-apart enlargements along the length of each of the two elongate resilient members;   
               

     two supporting frames each having a first support member, a second support member coupled perpendicular to the first support member, and a third support member couple perpendicular to the second support member and extending from the second support member in the same direction as the first support member,
         wherein the first support member and the third support member each comprise a cavity for receiving and holding one of the two elongate resilient members;       

     one or more guide members each having a base end and a remote end,
         wherein the one or more guide members is each independently connected to each of the two supporting frames and extending generally perpendicular thereto,   wherein the two first support members each independently comprise a first hole extending through each of the two first support members and generally parallel to the each of the two second support members; and       

     one cross member having a base end and a remote end,
         wherein the one cross member includes two connectors for independently securing one of the one or more spaced-apart enlargements along the length of each of the two elongate resilient members,   wherein the one or more connectors each extend through each of the one cross member and generally parallel to the one or more guide members and perpendicular to the two supporting frames,   wherein the one cross member rests at a point of equilibrium intermediate the base end and the remote end of each of two elongate resilient members;       

     displacing the one cross member; and 
     engaging the one or more spaced-apart enlargements in the one or more connectors to provide that the one cross member rests at a point of equilibrium intermediate the base end and the remote end of each of two elongate resilient members. 
     The present invention provides a bi-directional tensioning apparatus. The bi-directional tensioning apparatus includes: 
     one or more elongate resilient members each having a base end and a remote end,
         wherein the one or more elongate resilient members each comprise a first elastic material with one or more holes along the length of each of the one or more elongate resilient members;       

     one or more support members each having a base end and a remote end,
         wherein the one or more support members each comprise one or more optional first connectors at each base end and one or more second connectors at each remote end for receiving and holding the one or more holes along the length of each of the one or more elongate resilient members,   wherein the one or more optional first connectors at each base end and the one or more second connectors at each remote end each extend through or are on the exterior surface of each of the one or more support members and generally parallel to the one or more support members;       

     one or more first guide members each having a base end and a remote end,
         wherein the one or more first guide members is each independently connected at or proximate to the base end of each of the one or more support members and extending generally perpendicular thereto,   wherein the one or more first guide members each independently comprise one or more optional third connectors to receive and hold one of the one or more holes,   wherein the one or more optional third connectors each extend through or are on the exterior surface of each of the one or more first guide members and generally parallel to the one or more support members;       

     one or more optional couplers for independently securing one of the one or more holes; and 
     one or more optional second guide members each having a base end and a remote end,
         wherein each of the one or more optional second guide members is movably mounted on each of the one or more support members between the one or more first guide members and the remote end of each of the one or more support members and extending generally perpendicular thereto,   wherein the one or more optional second guide members each independently comprise a first snap-fit device on the base end and an optional second snap-fit device on the remote end for independently receiving one of the one or more support members,   wherein the one or more optional second guide members each comprise one or more fourth connectors for independently securing one of the one or more holes,   wherein the one or more fourth connectors each extend through or are on the exterior surface of each of the one or more optional second guide members and generally parallel to the one or more support members,   wherein the one or more optional second guide members each independently rest at a point of equilibrium intermediate the base end and the remote end of each of the one or more support members,   wherein the one or more optional first connectors, the one or more second connectors, the one or more optional third connectors and the one or more fourth connectors each independently comprise a compressible pin, a non-compressible pin, a hook, a nut and a bolt, or a combination thereof.       

     The present invention provides a bi-directional tensioning apparatus. The bi-directional tensioning apparatus includes: 
     two resilient members each having a base end and a remote end,
         wherein the two resilient members each comprise a first elastic material with one or more holes along the length of each of the two resilient members;       

     two support members each having a base end and a remote end,
         wherein the two support members each comprise a first connector at each remote end for receiving and holding the one or more holes along the length of each of the two resilient members,   wherein the first connectors at each remote end each extend through each of the two support members and generally parallel to the two support members;       

     a first guide member having a base end and a remote end,
         wherein the first guide member is connected at or proximate to the base end of each of the two support members and extending generally perpendicular thereto,   wherein the first guide member includes two second connectors to receive and hold one of the one or more holes on each of the two resilient members,   wherein the two second connectors each extend through the first guide member and are generally parallel to the two support members; and       

     a second guide member having a base end and a remote end,
         wherein the second guide member is movably mounted on each of the two support members between the first guide member and the remote end of each of the two support members and extending generally perpendicular thereto,   wherein the second guide member includes a first snap-fit device on the base end and a second snap-fit device on the remote end for independently receiving one of the two support members,   wherein the second guide member includes two third connectors for independently securing one of the one or more holes,   wherein the two third connectors each extend through each of the two second guide members and generally parallel to the two support members,   wherein the second guide member independently rest at a point of equilibrium intermediate the base end and the remote end of each of the two support members   wherein the two first connectors, the two second connectors, and the two third connectors each independently comprise a compressible pin, a non-compressible pin, a hook, a nut and a bolt, or a combination thereof.       

     The present invention provides a method for using a bi-directional tensioning apparatus. The method includes:
         providing a bi-directional tensioning apparatus including: two resilient members each having a base end and a remote end,   wherein the two resilient members each comprise a first elastic material with one or more holes along the length of each of the two resilient members;       

     two support members each having a base end and a remote end,
         wherein the two support members each comprise a first connector at each remote end for receiving and holding the one or more holes along the length of each of the two resilient members,   wherein the first connectors at each remote end each extend through each of the two support members and generally parallel to the two support members;       

     a first guide member having a base end and a remote end,
         wherein the first guide member is connected at or proximate to the base end of each of the two support members and extending generally perpendicular thereto,   wherein the first guide member includes two second connectors to receive and hold one of the one or more holes on each of the two resilient members,   wherein the two second connectors each extend through the first guide member and are generally parallel to the two support members; and       

     a second guide member having a base end and a remote end,
         wherein the second guide member is movably mounted on each of the two support members between the first guide member and the remote end of each of the two support members and extending generally perpendicular thereto,   wherein the second guide member includes a first snap-fit device on the base end and a second snap-fit device on the remote end for independently receiving one of the two support members,   wherein the second guide member includes two third connectors for independently securing one of the one or more holes,   wherein the two third connectors each extend through each of the two second guide members and generally parallel to the two support members,   wherein the second guide member independently rest at a point of equilibrium intermediate the base end and the remote end of each of the two support members   wherein the two first connectors, the two second connectors, and the two third connectors each independently comprise a compressible pin, a non-compressible pin, a hook, a nut and a bolt, or a combination thereof;       

     displacing the second member; and 
     engaging the one or more holes in the two third connectors to provide that the second guide member rests at a point of equilibrium intermediate the base end and the remote end of each of two elongate resilient members. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments of the invention may be best understood by referring to the following description and accompanying drawings, which illustrate such embodiments. In the drawings: 
         FIG. 1  is a front-view drawing illustrating an exemplary resilient member. 
         FIG. 2  is a perspective front-view drawing illustrating an exemplary bi-directional tensioning apparatus. 
         FIG. 3  is a perspective front-view drawing illustrating an exemplary bi-directional tensioning apparatus. 
         FIG. 4  is a top-view drawing illustrating an exemplary bi-directional tensioning apparatus. 
         FIG. 5  is a bottom-view drawing illustrating an exemplary bi-directional tensioning apparatus. 
         FIG. 6  is a perspective front-view drawing illustrating an exemplary bi-directional tensioning apparatus. 
         FIG. 7  is a top-view drawing illustrating an exemplary bi-directional tensioning apparatus. 
         FIG. 8  is a bottom-view drawing illustrating an exemplary portable structure. 
         FIG. 9  is a perspective front-view drawing illustrating an exemplary portable structure. 
         FIG. 10  is a perspective right-side view illustrating an exemplary portable structure. 
         FIG. 11  is a top-view drawing illustrating an exemplary portable structure. 
         FIG. 12  is a bottom-view illustrating an exemplary portable structure. 
         FIG. 13  is a top-view drawing illustrating an exemplary snap-fit connector. 
         FIG. 14  is a side-view drawing illustrating an exemplary snap-fit connector. 
         FIG. 15  is a perspective front-view drawing illustrating an exemplary bi-directional tensioning apparatus. 
         FIG. 16  is a front-view drawing illustrating an exemplary resilient member. 
         FIG. 17  is a perspective front-view drawing illustrating an exemplary bi-directional tensioning apparatus. 
         FIG. 18  is a top-view drawing illustrating an exemplary snap-fit connector. 
         FIG. 19  is a block diagram illustrating an exemplary method of assembling an exemplary bi-directional tensioning device. 
     
    
    
     The drawings are not necessarily to scale. Like numbers used in the figures refer to like components, steps and the like. However, it will be understood that the use of a number to refer to a component in a given figure is not intended to limit the component in another figure labeled with the same number. 
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention provides a bi-directional tensioning apparatus that includes, for example, an elongate resilient member, a support member, a first guide member, and a second guide member. The bi-directional tensioning apparatus is able to hold the second guide member in an equilibrium position intermediate the base end and the remote end of the support member. When a force is applied to the second guide member, the bi-directional tensioning apparatus exerts an opposing force. 
     The unique structure of the bi-directional tensioning apparatus preserves the elongate resilient member strength and integrity by not squeezing, bending, or constricting the elongate resilient member during use. Therefore, no weak spots in the elongate resilient member are created by tearing, shearing, and abrading. The elongate resilient member includes, for example, enlargements, which are captured by the support member, the first guide member, and the second guide member to provide bi-directional tension. 
     The bi-directional tensioning apparatus as describe herein, find applications, for example, tie-down equipment, exercise equipment, physical rehabilitation equipment, portable scaffolding, and the like. 
     The following detailed description includes references to the accompanying drawings, which form a part of the detailed description. The drawings show, by way of illustration, specific embodiments in which the invention may be practiced. These embodiments, which are also referred to herein as “examples,” are described in enough detail to enable those skilled in the art to practice the invention. The embodiments may be combined, other embodiments may be utilized, or structural, and logical changes may be made without departing from the scope of the present invention. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is defined by the appended claims and their equivalents. 
     Before the present invention is described in such detail, however, it is to be understood that this invention is not limited to particular variations set forth and may, of course, vary. Various changes may be made to the invention described and equivalents may be substituted without departing from the true spirit and scope of the invention. In addition, many modifications may be made to adapt a particular situation, material, composition of matter, process, process act(s) or step(s), to the objective(s), spirit or scope of the present invention. All such modifications are intended to be within the scope of the claims made herein. 
     Methods recited herein may be carried out in any order of the recited events which is logically possible, as well as the recited order of events. Furthermore, where a range of values is provided, it is understood that every intervening value, between the upper and lower limit of that range and any other stated or intervening value in that stated range is encompassed within the invention. Also, it is contemplated that any optional feature of the inventive variations described may be set forth and claimed independently, or in combination with any one or more of the features described herein. 
     The referenced items are provided solely for their disclosure prior to the filing date of the present application. Nothing herein is to be construed as an admission that the present invention is not entitled to antedate such material by virtue of prior invention. 
     Unless otherwise indicated, the words and phrases presented in this document have their ordinary meanings to one of skill in the art. Such ordinary meanings can be obtained by reference to their use in the art and by reference to general and scientific dictionaries, for example,  Webster&#39;s Third New International Dictionary , Merriam-Webster Inc., Springfield, Mass., 1993 , The American Heritage Dictionary of the English Language , Houghton Mifflin, Boston Mass., 1981, and  Hawley&#39;s Condensed Chemical Dictionary,  14 th  edition, Wiley Europe, 2002. 
     The following explanations of certain terms are meant to be illustrative rather than exhaustive. These terms have their ordinary meanings given by usage in the art and in addition include the following explanations. 
     As used herein, the term “about” refers to a variation of 10 percent of the value specified; for example about 50 percent carries a variation from 45 to 55 percent. 
     As used herein, the term “and/or” refers to any one of the items, any combination of the items, or all of the items with which this term is associated. 
     As used herein, the singular forms “a,” “an,” and “the” include plural reference unless the context clearly dictates otherwise. It is further noted that the claims may be drafted to exclude any optional element. As such, this statement is intended to serve as antecedent basis for use of such exclusive terminology as “solely,” “only,” and the like in connection with the recitation of claim elements, or use of a “negative” limitation. 
     As used herein, the term “coupled” means the joining of two members directly or indirectly to one another. Such joining may be stationary in nature or movable in nature and/or such joining may allow for the flow of fluids, electricity, electrical signals, or other types of signals or communication between two members. Such joining may be achieved with the two members or the two members and any additional intermediate members being integrally formed as a single unitary body with one another or with the two members or the two members and any additional intermediate members being attached to one another. Such joining may be permanent in nature or alternatively may be removable or releasable in nature. 
     As used herein, the terms “include,” “for example,” “such as,” and the like are used illustratively and are not intended to limit the present invention. 
     As used herein, the terms “preferred” and “preferably” refer to embodiments of the invention that may afford certain benefits, under certain circumstances. However, other embodiments may also be preferred, under the same or other circumstances. Furthermore, the recitation of one or more preferred embodiments does not imply that other embodiments are not useful, and is not intended to exclude other embodiments from the scope of the invention. 
     As used herein, the terms “front,” “back,” “rear,” “upper,” “lower,” “right,” and “left” in this description are merely used to identify the various elements as they are oriented in the FIGS, with “front,” “back,” and “rear” being relative apparatus. These terms are not meant to limit the element which they describe, as the various elements may be oriented differently in various applications. 
       FIG. 1  is a front-view drawing illustrating an exemplary resilient member  100 . The resilient member  100  having a base end  101  and a remote end  102 . The resilient member  100  includes a first enlargement  103  at the base end and spaced-apart enlargements  104  along the length of the resilient member  100 . 
     In one embodiment, the resilient member  100  may be made of for example, a styrene-butadiene rubber or a chloroprene (i.e., neoprene) rubber. The resilient member  100  has excellent memory characteristics and returns to its original shape after numerous elongations. 
     The resilient member  100  may also be made of any other suitable elastic material, for example, natural rubber, synthetic polyisoprene, butyl rubber (copolymer of isobutylene and isoprene), halogenated butyl rubber, polybutadiene, nitrile butadiene rubber, hydrogenated nitrile rubber, ethylene propylene rubber, epichlorohydrin rubber, polyacrylic rubber, silicone rubber, fluorosilicon rubber, fluoroelastomers, prefluoroelastomers, thermoplastic polyurethane, polyether block amides, chlorosulfonated polyethylene, ethylene-vinyl acetate, and the like, or combinations thereof. 
     Typical physical properties for a suitable elastic material includes, for example, a polymer specific gravity from about 0.8 to about 2.0, a tensile strength (in pounds per square inch) from about 1000 to about 9000, and a percentage elongation to about 900. The elastic material should also possess, for example, good abrasion resistance, good tear resistance, and good ozone resistance. 
     In one embodiment, the exemplary resilient member  100  may be, for example, a bungee cord, which is an elastic cord composed of one or more elastic strands forming a core, usually covered in a woven nylon or cotton sheath. 
     In one embodiment, the first enlargement  103  at the base end and each of the one or more spaced-apart enlargements  104  is made of the elastic material. In one embodiment, the first enlargement  103  at the base end is made of the elastic material and each of the one or more spaced-apart enlargements  104  are made of a wooden material. In one embodiment, the first enlargement  103  at the base end is made of the elastic material and each of the one or more spaced-apart enlargements  104  are made of a metal material. 
     In one embodiment, the first enlargement  103  at the base end is made of the elastic material and each of the one or more spaced-apart enlargements  104  are made of a plastic material. In one embodiment, the first enlargement  103  at the base end is made of the elastic material and each of the one or more spaced-apart enlargements  104  are made of a different elastic material. In one embodiment, the first enlargement  103  at the base end is made of a wooden material and each of the one or more spaced-apart enlargements  104  are made of an elastic material. 
     In one embodiment, the first enlargement  103  at the base end is made of a wooden material and each of the one or more spaced-apart enlargements  104  are made of a wooden material. In one embodiment, the first enlargement  103  at the base end is made of a wooden material and each of the one or more spaced-apart enlargements  104  are made of a metal material. In one embodiment, the first enlargement  103  at the base end is made of a wooden material and each of the one or more spaced-apart enlargements  104  are made of a plastic material. 
     In one embodiment, the first enlargement  103  at the base end is made of a metal material and each of the one or more spaced-apart enlargements  104  are made of an elastic material. In one embodiment, the first enlargement  103  at the base end is made of a metal material and each of the one or more spaced-apart enlargements  104  are made of a wooden material. In one embodiment, the first enlargement  103  at the base end is made of a metal material and each of the one or more spaced-apart enlargements  104  are made of a metal material. In one embodiment, the first enlargement  103  at the base end is made of a metal material and each of the one or more spaced-apart enlargements  104  are made of a plastic material. 
     In one embodiment, the first enlargement  103  at the base end is made of a plastic material and each of the one or more spaced-apart enlargements  104  are made of an elastic material. In one embodiment, the first enlargement  103  at the base end is made of a plastic and each of the one or more spaced-apart enlargements  104  are made of a wooden material. In one embodiment, the first enlargement  103  at the base end is made of a plastic material and each of the one or more spaced-apart enlargements  104  are made of a metal material. In one embodiment, the first enlargement  103  at the base end is made of a plastic material and each of the one or more spaced-apart enlargements  104  are made of a plastic material. 
     In one embodiment, the first enlargement  103  at the base end and each of the one or more spaced-apart enlargements  104  is made of a knot of the elastic material. In one embodiment, the first enlargement  103  at the base end is made of elastic material and each of the one or more spaced-apart enlargements  104  is made of a knot of the elastic material. In one embodiment, the first enlargement  103  at the base end is made of a knot of the elastic material and each of the one or more spaced-apart enlargements  104  is made of the elastic material. 
     In one embodiment, the first enlargement  103  at the base end is made of knot of the elastic material and each of the one or more spaced-apart enlargements  104  are made of a wooden material. In one embodiment, the first enlargement  103  at the base end is made of wooden material and each of the one or more spaced-apart enlargements  104  are made of a knot of the elastic material. 
     In one embodiment, the first enlargement  103  at the base end is made of knot of the elastic material and each of the one or more spaced-apart enlargements  104  are made of a different elastic material. In one embodiment, the first enlargement  103  at the base end is made of a different elastic material and each of the one or more spaced-apart enlargements  104  are made of a knot of the elastic material. 
     In one embodiment, the first enlargement  103  at the base end is made of a metal material and each of the one or more spaced-apart enlargements  104  are made of a knot of the elastic material. In one embodiment, the first enlargement  103  at the base end is made of a knot of the elastic material and each of the one or more spaced-apart enlargements  104  are made of a metal material. 
     The first enlargement  103  may be, for example, of any shape that prevents the resilient member  100  from sliding through one of the first guide members described herein. The first enlargement  103  may be, for example, a cylindrical shape, a spherical shape, a square shape, a polygonal shape, and the like. Preferably, the first enlargement  103  has a cylindrical shape. More preferably, the first enlargement  103  has a cylindrical shape with a bevel edge on the side of the first enlargement  103  opposite the first guide member to provide reinforcement. 
       FIG. 2  is a perspective front-view drawing illustrating an exemplary bi-directional tensioning apparatus  200 . The bi-directional tensioning apparatus  200  typically includes a support member  201 , a first guide member  202 , a second guide member  203 , and elongate resilient member  204 . The first guide member  202  includes a first coupler  205  and a first cylindrical tube  206 . The first cylindrical tube  206  has an outside and an inside diameters equal to that the support member  201 . The first cylindrical tube  206  also contains a first hole  207  extending perpendicular through the first cylindrical tube  206 . When the first cylindrical tube  206  is attached to the first coupler  205 , the first hole  207  is oriented in the direction parallel to the support member  201 . The first hole  207  will allow the elongate resilient member  204  to pass through it up to the first enlargement. 
     The first hole  207  may be of any shape that can allow the remote end of the elongate resilient member  204  to pass through. In one embodiment, the elongate resilient member  204  has a circular cross section and the first hole  207  has a circular shape. In another embodiment, the elongate resilient member  204  has a polygonal cross section and the first hole  207  has the same polygonal shape. 
     In one embodiment, the first hole  207  has a surface recessed cavity (not shown) in a shape complementary to the shape of the first enlargement of the elongate resilient member  204  to form a tight fit under pressure. 
     In one embodiment, the first enlargement of the elongate resilient member  204  has a spherical shape and the recessed cavity (not shown) in the first hole  207  also has a complementary spherical shape. In one embodiment, the first enlargement of the elongate resilient member  204  has a cylindrical shape and the recessed cavity (not shown) in the first hole  207  also has a complementary cylindrical shape. In one embodiment, the first enlargement of the elongate resilient member  204  has a polygonal shape and the recessed cavity (not shown) in the first hole  207  also has a complementary polygonal shape. 
     One end of the first coupler  205  is rigidly secured to a base end of the support member  201 , by adhesive or any other suitable means. A separate hole (not shown) is formed in the cylindrical sidewall of the first coupler  205 , proximate the end of the support member  201 . A corresponding hole (not shown) is formed through the cylindrical sidewall of the first cylindrical tube  206  proximate the end thereof. A snap button, of the type known in the art, is inserted into the corresponding hole (not shown) on one end of the first cylindrical tube  206 , so that the first snap button  208  protrudes out of the hole. One end of the first cylindrical tube  206  is then inserted or “telescoped” into the first coupler  205  and arranged so that the first snap button  208  engages the hole through the sidewall thereof. In this manner, the first cylindrical tube  206  is releasably connected to the support member  201 . The support member  201  extends linearly from its base end  209  to a remote end  210 . The second guide member  203  includes the second coupler  211  and the second cylindrical tube  212 . The second coupler  211  may be a snap-fit connector. An exemplary snap-fit connector is described herein below and shown in  FIGS. 13-14 . 
     The second cylindrical tube  212  has an outside and an inside diameter equal to that the support member  201 . A corresponding hole (not shown) is formed through the cylindrical sidewall of the second cylindrical tube  212  proximate the end thereof. A snap button, of the type known in the art, is inserted into one end of the second cylindrical tube  212 , so that the second snap button  213  protrudes out of the hole. One end of the second cylindrical tube  212  is then inserted or “telescoped” into the second coupler  211  and arranged so that the second snap button  213  engages the hole through the sidewall thereof. In this manner, the second cylindrical tube  212  is releasably connected to the support member  201 . The second cylindrical tube  212  also contains a keyhole  214  also extending perpendicular through the second cylindrical tube  212 . When the second cylindrical tube  212  is attached to the second coupler  211 , the keyhole  214  is oriented in the direction parallel to the support member  201 . The keyhole  214  will allow the first elongate resilient member  204  to pass through it and to engage one of the spaced-apart enlargements (not shown). Exemplary keyholes are described herein below and shown in  FIG. 13 . 
     A stop  215  is secured to the remote end  210  of the support member  201 . The stop  215  contains a cavity  216  that captures and secures the elongate resilient member  204 . The stop  215  may be secured to the support member  201  by a snap button (not shown) or any other suitable means. 
     In one embodiment, the second guide member  203  includes the second coupler  211  and the second cylindrical tube  212 . In another embodiment, the second guide member  203  is a second cylindrical tube (not shown) with a coupler end. 
     A person can use the bi-directional tensioning apparatus  200  to perform a variety of exercises. The relative movement of the second guide member  203  toward or away from the first guide member  202 , as indicated by the double arrow, increases the tension in the first elongate resilient member  204 . For example, a person can perform a “fly” exercise by extending the hands generally forward, grasping the first guide member  202  in one hand, grasping the second guide member  203  in the other hand, and pressing the hands toward one another; a person can perform a “sitting knee curl” exercise by sitting on a chair, capturing the first guide member  202  between the floor and at least one foot, resting the elbows on the knees with the hands extending generally forward, grasping the second guide member  203  in opposite hands, and pulling upward and inward on the second guide member  203 ; a person can perform an “inner thigh squeeze” exercise by sitting on a chair, placing one knee against the outside of the first guide member  202 , placing the other knee against the outside of the second guide member  203 , and pressing the knees toward one another; and/or a person can perform an “outer thigh exercise by sitting on a chair, placing one knee against the inside of the first guide member  202 , placing the other knee against the inside of the second guide member  203 , and pressing the knees away from one another. When not in use, the exercise apparatus  200  may be collapsed, by removing the first cylindrical tube  206 , the second cylindrical tube  212 , and the elongate resilient member  204  to facilitate storage and/or transportation of the bi-directional tensioning apparatus  200 . If adjustability of the amount of resistance is desired, the elongate resilient member  204  may be selectively moved relative to cavity  216 . 
       FIG. 3  is a perspective front-view drawing illustrating an exemplary bi-directional tensioning apparatus  300 . The bi-directional tensioning apparatus  300  typically includes a support member  301 , a first guide member  302 , a second guide member  303 , first elongate resilient member  304 , and second elongate resilient member  305 . The first guide member  302  includes a first coupler  306 , a second coupler  307 , a first cylindrical tube  308 , and a second cylindrical tube  309 . The first cylindrical tube  308  and the second cylindrical tube  309  have outside and inside diameters equal to that the support member  301 . The first cylindrical tube  308  also contains a first hole  310  extending perpendicular through the first cylindrical tube  308 . The second cylindrical tube  309  also contains a second hole  311  also extending perpendicular through the second cylindrical tube  309 . When the first cylindrical tube  308  and the second cylindrical tube  309  are attached to the first coupler  306  and the second coupler  307 , respectively, the first hole  310  and the second hole  311  are oriented in the direction parallel to the support member  301 . The first hole  310  will allow the first elongate resilient member  304  to pass through it up to the first enlargement. The second hole  311  will allow the second elongate resilient member  305  to pass through it up to the first enlargement. 
     One end of the first coupler  306  is rigidly secured to a base end of the support member  301 , by adhesive or any other suitable means. One end of the second coupler  307  is rigidly secured to a base end of the support member  301 , by adhesive or any other suitable means. A separate hole (not shown) is formed in the cylindrical sidewall of each of the couplers  306  and  307 , proximate the end of the support member  301 . Corresponding holes (not shown) are formed through the cylindrical sidewall of the first cylindrical tube  308  and the second cylindrical tube  309  proximate each end thereof. Snap buttons, of the type known in the art, are inserted into the corresponding hole (not shown) on one end of the first cylindrical tube  308  and into the corresponding hole (not shown) on one end of the second cylindrical tube  309 , so that the first snap button  312  and the second snap button  313  each protrude out of their respective holes. One end of the first cylindrical tube  308  is then inserted or “telescoped” into the first coupler  306  and arranged so that the first snap button  312  engages the hole through the sidewall thereof. One end of the second cylindrical tube  309  is then inserted or “telescoped” into the second coupler  307  and arranged so that the second snap button  313  engages the hole through the sidewall thereof. In this manner, the first cylindrical tube  308  and the second cylindrical tube  309  are releasably connected to the support member  301 . The support member  301  extends linearly from its base end  314  to a remote end  315 . The second guide member  303  includes the four-way coupler  316 , a third cylindrical tube  317 , and a fourth cylindrical tube  318 . The third cylindrical tube  317  and the fourth cylindrical tube  318  have outside and inside diameters equal to that the support member  301 . Corresponding holes are formed through the cylindrical sidewall of the third cylindrical tube  317  and the fourth cylindrical tube  318  proximate each end thereof. Snap buttons, of the type known in the art, are inserted into one end of the third cylindrical tube  317  and one end of the fourth cylindrical tube  318 , so that the third snap button  319  and the fourth snap button  320  each protrude out of their respective holes. One end of the third cylindrical tube  317  is then inserted or “telescoped” into the four-way coupler  316  and arranged so that the third snap button  319  engages the hole through the sidewall thereof. One end of the fourth cylindrical tube  318  is then inserted or “telescoped” into the opposite side of the four-way coupler  316  and arranged so that the fourth snap button  320  engages the hole through the sidewall thereof. In this manner, the third cylindrical tube  317  and the fourth cylindrical tube  318  are releasably connected to the support member  301 . The third cylindrical tube  317  also contains a first keyhole  321  extending perpendicular through the third cylindrical tube  317 . The fourth cylindrical tube  318  also contains a second keyhole  322  also extending perpendicular through the fourth cylindrical tube  318 . When the third cylindrical tube  317  and the fourth cylindrical tube  318  are attached to the four-way coupler  316 , respectively, the first keyhole  321  and the second keyhole  322  are oriented in the direction parallel to the support member  301 . The first keyhole  321  will allow the first elongate resilient member  304  to pass through it and to engage one of the spaced-apart enlargements (not shown). The second keyhole  322  will allow the second elongate resilient member  305  to pass through it and to engage one of the spaced-apart enlargements (not shown). Exemplary keyholes are described herein below and shown in  FIG. 13 . 
     The first hole  310  may be of any shape that can allow the remote end of the first elongate resilient member  304  to pass through. In one embodiment, the first elongate resilient member  304  has a circular cross section and the first hole  310  has a circular shape. In another embodiment, the first elongate resilient member  304  has a polygonal cross section and the first hole  310  has the same polygonal shape. 
     In one embodiment, the first hole  310  has a surface recessed cavity (not shown) in a shape complementary to the shape of the first enlargement of the first elongate resilient member  304  to form a tight fit under pressure. 
     In one embodiment, the first enlargement of the first elongate resilient member  304  has a spherical shape and the recessed cavity (not shown) in the first hole  310  also has a complementary spherical shape. In one embodiment, the first enlargement of the first elongate resilient member  304  has a cylindrical shape and the recessed cavity (not shown) in the first hole  310  also has a complementary cylindrical shape. In one embodiment, the first enlargement of the first elongate resilient member  304  has a polygonal shape and the recessed cavity (not shown) in the first hole  310  also has a complementary polygonal shape. 
     The second hole  311  may be of any shape that can allow the remote end of the second elongate resilient member  305  to pass through. In one embodiment, the second elongate resilient member  305  has a circular cross section and the second hole  311  has a circular shape. In another embodiment, the second elongate resilient member  305  has a polygonal cross section and the second hole  311  has the same polygonal shape. 
     In one embodiment, the second hole  311  has a surface recessed cavity (not shown) in a shape complementary to the shape of the first enlargement of the second elongate resilient member  305  to form a tight fit under pressure. 
     In one embodiment, the first enlargement of the second elongate resilient member  305  has a spherical shape and the recessed cavity (not shown) in the second hole  311  also has a complementary spherical shape. In one embodiment, the first enlargement of the second elongate resilient member  305  has a cylindrical shape and the recessed cavity (not shown) in the second hole  311  also has a complementary cylindrical shape. In one embodiment, the first enlargement of the second elongate resilient member  305  has a polygonal shape and the recessed cavity (not shown) in the second hole  311  also has a complementary polygonal shape. 
     A stop  323  is secured to the remote end  315  of the support member  301 . The stop  323  contains a cavity  324  that captures and secures both the first elongate resilient member  304  and the second elongate resilient member  305 . The stop  323  may be secured to the support member  301  by a snap button (not shown) or any other suitable means. In another embodiment, the stop  323  contains two cavities that each independently captures and secures both the first elongate resilient member  304  and the second elongate resilient member  305 . 
     The relative movement of the second guide member  303  toward or away from the first guide member  302 , as indicated by the double arrows, increases the tension in the first elongate resilient member  304  and the second elongate resilient member  305 . 
       FIG. 4  is a top-view drawing illustrating an exemplary bi-directional tensioning apparatus  300 . The bi-directional tensioning apparatus  300  typically includes a support member  301 , a first guide member  302 , first elongate resilient member  304 , and second elongate resilient member  305 . The first guide member  302  includes the first coupler  306 , the second coupler  307 , the first cylindrical tube  308 , the second cylindrical tube  309 , the first snap button  312 , and the second snap button  313 . 
       FIG. 5  is a bottom-view drawing illustrating an exemplary bi-directional tensioning apparatus  300 . The bi-directional tensioning apparatus  300  typically includes a support member  301 , and the second guide member  303 . The second guide member  303  includes the four-way coupler  316 , a third cylindrical tube  317 , a fourth cylindrical tube  318 , the first keyhole  321  and the second keyhole  322 . The bottom or remote end of the support member  301  includes the stop  323 , which contains the cavity  324 . 
     Those skilled in the art will also recognize that bi-directional tensioning apparatus  300  may also be used with the first elongate resilient member  304  or with the second elongate resilient member  305 , or with more than two elongate resilient members to facilitate additional bi-directional tensioning and/or resistance curves. 
     A person can use the bi-directional tensioning apparatus  300  to perform a variety of exercises. For example, a person can perform a “chest press” exercise by placing the base end  314  of the support member  301  on their chest, extending the hands generally forward, grasping the second guide member  303  in opposite hands, and pressing outward with the arms; a person can perform a “fly” exercise by extending the hands generally forward, grasping the first guide member  302  in one hand, grasping the second guide member  303  in the other hand, and pressing the hands toward one another; a person can perform a “sitting knee curl” exercise by sitting on a chair, capturing the first guide member  302  between the floor and at least one foot, resting the elbows on the knees with the hands extending generally forward, grasping the second guide member  303  in opposite hands, and pulling upward and inward on the second guide member  303 ; a person can perform a “standing curl” exercise by placing the first guide member  302  behind the buttocks, extending the hands generally downward, grasping the second guide member  303  in opposite hands in opposite hands, and pulling upward and inward on the second guide member  303 ; a person can perform a “military press” exercise by placing the first guide member  302  behind the head and across the shoulders, extending the hands generally above the head, grasping the second guide member  303  in opposite hands, and pulling downward on the second guide member  303 ; a person can perform a “squat” exercise by placing the first guide member  302  on the floor, standing on the first guide member  302 , extending the hands generally downward, grasping the second guide member  303  in opposite hands, and pulling upward on the second guide member  303 ; a person can perform a “sit up” exercise by sitting on a chair, placing the first guide member  302  across the lap, capturing the second guide member  303  beneath the arms, and pushing downward on the second guide member  303 ; a person can perform an “inner thigh squeeze” exercise by sitting on a chair, placing one knee against the outside of the first guide member  302 , placing the other knee against the outside of the second guide member  303 , and pressing the knees toward one another; and/or a person can perform an “outer thigh exercise by sitting on a chair, placing one knee against the inside of the first guide member  302 , placing the other knee against the inside of the second guide member  303 , and pressing the knees away from one another. When not in use, the exercise apparatus  300  may be collapsed, by removing the first cylindrical tube  308 , the second cylindrical tube  309 , the third cylindrical tube  317 , the fourth cylindrical tube  318 , the first elongate resilient member  304 , and the second elongate resilient member  305  to facilitate storage and/or transportation of the bi-directional tensioning apparatus  300 . If adjustability of the amount of resistance is desired, the first elongate resilient member  304  and the second elongate resilient member  305  may be selectively moved relative cavity  324 . 
       FIG. 6  is a perspective front-view drawing illustrating an exemplary bi-directional tensioning apparatus  400 . The bi-directional tensioning apparatus  400  typically includes a first support member  401 , a second support member  402 , a first guide member  403 , a second guide member  404 , a first elongate resilient member  405 , and a second elongate resilient member  406 . The first guide member  403  includes a first coupler  407 , a second coupler  408 , and a first cylindrical tube  409 . The first cylindrical tube  409  has an outside and an inside diameter equal to that the first support member  401 . The first cylindrical tube  409  also contains a first hole  410  and a second hole  411  both extending perpendicular through the first cylindrical tube  409 . When the first cylindrical tube  409  is attached to the first coupler  407  and the second coupler  408 , the first hole  410  and the second hole  411  are oriented in the direction parallel to the first support member  401  and the second support member  402 . The first hole  410  will allow the first elongate resilient member  405  to pass through it up to the first enlargement. The second hole  411  will allow the second elongate resilient member  406  to pass through it up to the first enlargement. 
     One end of the first coupler  407  is rigidly secured to a base end of the first support member  401 , by adhesive or any other suitable means. One end of the second coupler  408  is rigidly secured to a base end of the second support member  402 , by adhesive or any other suitable means. A separate hole is formed in the cylindrical sidewall of each of the first coupler  407  and the second coupler  408 , proximate the end of the first support member  401  and the second support member  402 , respectively. Corresponding holes (not shown) are formed through the cylindrical sidewall of the first cylindrical tube  409  proximate the opposite ends thereof. Snap buttons, of the type known in the art, are inserted into the corresponding hole (not shown) on opposite ends of the first cylindrical tube  409 , so that the first snap button  412  and the second snap button  413  each protrude out of their respective holes. One end of the first cylindrical tube  409  is then inserted or “telescoped” into the first coupler  407  and arranged so that the first snap button  412  engages the hole through the sidewall thereof. The opposite end of the first cylindrical tube  409  then inserted or “telescoped” into the second coupler  408  and arranged so that the second snap button  413  engages the hole through the sidewall thereof. In this manner, the first cylindrical tube  409  is releasably connected to the first support member  401  and the second support member  402 . The first support member  401  extends linearly from its base end  414  to a remote end  415 . 
     The second guide member  404  includes a first snap-fit connector  416 , a second snap-fit connector  417 , and a second cylindrical tube  418 . An exemplary snap-fit connector is described herein below and shown in  FIGS. 13-14 . The second cylindrical tube  418  has outside and inside diameter equals to that the first support member  401  and the second support member  402 . 
     The first snap-fit connector  416  also contains a first keyhole  419  extending perpendicular through the first snap-fit connector  416 . The second snap-fit connector  417  also contains a second keyhole  420  also extending perpendicular through the second snap-fit connector  417 . When the second cylindrical tube  418  is attached to both of the first snap-fit connector  416  and the second snap-fit connector  417 , the first keyhole  419  and the second keyhole  420  are oriented in the direction parallel to the first support member  401  and the second support member  402 . The first keyhole  419  will allow the first elongate resilient member  405  to pass through it and to engage one of the spaced-apart enlargements (not shown). The second keyhole  420  will allow the second elongate resilient member  406  to pass through it and to engage one of the spaced-apart enlargements (not shown). Exemplary keyholes are described herein below and shown in  FIG. 13 . 
     The first hole  410  may be of any shape that can allow the remote end of the first elongate resilient member  405  to pass through. In one embodiment, the first elongate resilient member  405  has a circular cross section and the first hole  410  has a circular shape. In another embodiment, the first elongate resilient member  405  has a polygonal cross section and the first hole  410  has the same polygonal shape. 
     In one embodiment, the first hole  410  has a surface recessed cavity (not shown) in a shape complementary to the shape of the first enlargement of the first elongate resilient member  405  to form a tight fit under pressure. 
     In one embodiment, the first enlargement of the first elongate resilient member  405  has a spherical shape and the recessed cavity (not shown) in the first hole  410  also has a complementary spherical shape. In one embodiment, the first enlargement of the first elongate resilient member  405  has a cylindrical shape and the recessed cavity (not shown) in the first hole  410  also has a complementary cylindrical shape. In one embodiment, the first enlargement of the first elongate resilient member  405  has a polygonal shape and the recessed cavity (not shown) in the first hole  410  also has a complementary polygonal shape. 
     The second hole  411  may be of any shape that can allow the remote end of the second elongate resilient member  406  to pass through. In one embodiment, the second elongate resilient member  406  has a circular cross section and the second hole  411  has a circular shape. In another embodiment, the second elongate resilient member  406  has a polygonal cross section and the second hole  411  has the same polygonal shape. 
     In one embodiment, the second hole  411  has a surface recessed cavity (not shown) in a shape complementary to the shape of the first enlargement of the second elongate resilient member  406  to form a tight fit under pressure. 
     In one embodiment, the first enlargement of the second elongate resilient member  406  has a spherical shape and the recessed cavity (not shown) in the second hole  411  also has a complementary spherical shape. In one embodiment, the first enlargement of the elongate resilient member  406  has a cylindrical shape and the recessed cavity (not shown) in the second hole  411  also has a complementary cylindrical shape. In one embodiment, the first enlargement of the elongate resilient member  406  has a polygonal shape and the recessed cavity (not shown) in the second hole  411  also has a complementary polygonal shape. 
     A first stop  421  is secured to the remote end  415  of the first support member  401 . The first stop  421  contains a first cavity  422  that captures and secures and the first elongate resilient member  405 . The first stop  421  may be secured to the first support member  401  by a snap button (not shown) or any other suitable means. 
     A second stop  423  is secured to the remote end of the second support member  402 . The second stop  423  contains a second cavity  424  that captures and secures and the second elongate resilient member  406 . The second stop  423  may be secured to the second support member  402  by a snap button (not shown) or any other suitable means. 
     Those skilled in the art will also recognize that bi-directional tensioning apparatus  400  may also be used with the first elongate resilient member  405  or with the second elongate resilient member  406 , or with more than two elongate resilient members to facilitate additional bi-directional tensioning and/or resistance curves. 
       FIG. 7  is a top-view drawing illustrating an exemplary bi-directional tensioning apparatus  400 . The bi-directional tensioning apparatus  400  typically includes the first support member  401 , the second support member  402 , and the first guide member  403 , the first elongate resilient member  405 , and the second elongate resilient member  406 . The first guide member  403  includes the first coupler  407 , the second coupler  408 , the first cylindrical tube  409 , the first snap button  412 , and the second snap button  413 . 
       FIG. 8  is a bottom-view drawing illustrating an exemplary bi-directional tensioning apparatus  400 . The bi-directional tensioning apparatus  400  typically includes the first support member  401 , the second support member  402 , and the second guide member  404 . The second guide member  404  includes the first snap-fit connector  416 , the second snap-fit connector  417 , the second cylindrical tube  418 , the first keyhole  419 , and the second keyhole  420 . The bottom or remote end of the first support member  401  includes the first stop  421 , which contains the first cavity  422 . The bottom or remote end of the second support member  402  includes the second stop  423 , which contains the second cavity  424 . 
     The relative movement of the second guide member  404  toward or away from the first guide member  403 , as indicated by the double arrows, increases the tension in the first elongate resilient member  405  and the second elongate resilient member  406 . 
     A person can use the bi-directional tensioning apparatus  400  to perform a variety of exercises. For example, a person can perform a “chest press” exercise by placing the first guide member  403  on their chest, extending the hands generally forward, grasping the second guide member  404  in opposite hands, and pressing outward with the arms; a person can perform a “fly” exercise by extending the hands generally forward, grasping the first guide member  403  in one hand, grasping the second guide member  404  in the other hand, and pressing the hands toward one another; a person can perform a “sitting knee curl” exercise by sitting on a chair, capturing the first guide member  403  between the floor and at least one foot, resting the elbows on the knees with the hands extending generally forward, grasping the second guide member  404  with opposite hands, and pulling upward and inward on the second guide member  404 ; a person can perform a “standing curl” exercise by placing the first guide member  403  behind the buttocks, extending the hands generally downward, grasping the second guide member  404  in opposite hands, and pulling upward and inward on the second guide member  404 ; a person can perform a “military press” exercise by placing the first guide member  403  behind the head and across the shoulders, extending the hands generally above the head, grasping the second guide member  404  with opposite hands, and pulling downward on the second guide member  404 ; a person can perform a “squat” exercise by placing the first guide member  403  on the floor, standing on the first guide member  403 , extending the hands generally downward, grasping the second guide member  404  in opposite hands, and pulling upward on the second guide member  404 ; a person can perform a “sit up” exercise by sitting on a chair, placing the first guide member  403  across the lap, capturing the second guide member  404  beneath the arms, and pushing downward on the second guide member  404 ; a person can perform an “inner thigh squeeze” exercise by sitting on a chair, placing one knee against the outside of the first support member  401 , placing the other knee against the outside of the second support member  402 , and pressing the knees toward one another; and/or a person can perform an “outer thigh exercise by sitting on a chair, placing one knee against the inside of the first guide member  403 , placing the other knee against the inside of the second guide member  404 , and pressing the knees away from one another. When not in use, the bi-directional tensioning apparatus  400  may be collapsed, by removing the first guide member  403 , the second guide member  404 , the first elongate resilient member  405 , and the second elongate resilient member  406  to facilitate storage and/or transportation of the bi-directional tensioning apparatus  400 . If adjustability of the amount of resistance is desired, the first elongate resilient member  405  and the second elongate resilient member  406  may be selectively moved relative each cavity  422  and  424 , respectively. 
       FIG. 9  is a perspective front-view drawing illustrating an exemplary portable structure  500  that may be made using the bi-directional tensioning apparatus described herein. The portable structure  500  typically includes a first support member  501 , a second support member  502 , a first guide member  503 , a second guide member  504 , a first elongate resilient member  505 , and a second elongate resilient member  506 . The first guide member  503  includes a first coupler  507 , a second coupler  508 , and a first cylindrical tube  509 . The first cylindrical tube  509  has an outside and an inside diameter equal to that the first support member  501 . The first cylindrical tube  509  also contains a first hole  510  and a second hole  511  both extending perpendicular through the first cylindrical tube  509 . When the first cylindrical tube  509  is attached to the first coupler  507  and the second coupler  508 , the first hole  510  and the second hole  511  are oriented in the direction parallel to the first support member  501  and the second support member  502 . The first hole  510  will allow the first elongate resilient member  505  to pass through it up to the first enlargement. The second hole  511  will allow the second elongate resilient member  506  to pass through it up to the first enlargement. 
     One end of the first coupler  507  is rigidly secured to a base end of the first support member  501 , by adhesive or any other suitable means. One end of the second coupler  508  is rigidly secured to a base end of the second support member  502 , by adhesive or any other suitable means. A separate hole is formed in the cylindrical sidewall of each of the first coupler  507  and the second coupler  508 , proximate the end of the first support member  501  and the second support member  502 , respectively. Corresponding holes (not shown) are formed through the cylindrical sidewall of the first cylindrical tube  509  proximate the opposite ends thereof. Snap buttons, of the type known in the art, are inserted into the corresponding hole (not shown) on opposite ends of the first cylindrical tube  509 , so that the first snap button  512  and the second snap button  513  each protrude out of their respective holes. One end of the first cylindrical tube  509  is then inserted or “telescoped” into the first coupler  507  and arranged so that the first snap button  512  engages the hole through the sidewall thereof. The opposite end of the first cylindrical tube  509  then inserted or “telescoped” into the second coupler  508  and arranged so that the second snap button  513  engages the hole through the sidewall thereof. In this manner, the first cylindrical tube  509  is releasably connected to the first support member  501  and the second support member  502 . The first support member  501  extends linearly from its base end  514  to a remote end  515 . 
     The second guide member  504  includes a first snap-fit connector  516 , a second snap-fit connector  517 , and a second cylindrical tube  518 . An exemplary snap-fit connector is described herein below and shown in  FIGS. 13-14 . The second cylindrical tube  518  has outside and inside diameter equals to that the first support member  501  and the second support member  502 . 
     The first snap-fit connector  516  also contains a first keyhole  519  extending perpendicular through the first snap-fit connector  516 . The second snap-fit connector  517  also contains a second keyhole  520  also extending perpendicular through the second snap-fit connector  517 . When the second cylindrical tube  518  is attached to both of the first snap-fit connector  516  and the second snap-fit connector  517 , the first keyhole  519  and the second keyhole  520  are oriented in the direction parallel to the first support member  501  and the second support member  502 . The first keyhole  519  will allow the first elongate resilient member  505  to pass through it and to engage one of the spaced-apart enlargements (not shown). The second keyhole  520  will allow the second elongate resilient member  506  to pass through it and to engage one of the spaced-apart enlargements (not shown). Exemplary keyholes are described herein below and shown in  FIG. 13 . 
     The first hole  510  may be of any shape that can allow the remote end of the first elongate resilient member  505  to pass through. In one embodiment, the first elongate resilient member  505  has a circular cross section and the first hole  510  has a circular shape. In another embodiment, the first elongate resilient member  505  has a polygonal cross section and the first hole  510  has the same polygonal shape. 
     In one embodiment, the first hole  510  has a surface recessed cavity (not shown) in a shape complementary to the shape of the first enlargement of the first elongate resilient member  505  to form a tight fit under pressure. 
     In one embodiment, the first enlargement of the first elongate resilient member  505  has a spherical shape and the recessed cavity (not shown) in the first hole  510  also has a complementary spherical shape. In one embodiment, the first enlargement of the first elongate resilient member  505  has a cylindrical shape and the recessed cavity (not shown) in the first hole  510  also has a complementary cylindrical shape. In one embodiment, the first enlargement of the first elongate resilient member  505  has a polygonal shape and the recessed cavity (not shown) in the first hole  510  also has a complementary polygonal shape. 
     The second hole  511  may be of any shape that can allow the remote end of the second elongate resilient member  506  to pass through. In one embodiment, the second elongate resilient member  506  has a circular cross section and the second hole  511  has a circular shape. In another embodiment, the second elongate resilient member  506  has a polygonal cross section and the second hole  511  has the same polygonal shape. 
     In one embodiment, the second hole  511  has a surface recessed cavity (not shown) in a shape complementary to the shape of the first enlargement of the second elongate resilient member  506  to form a tight fit under pressure. 
     In one embodiment, the first enlargement of the second elongate resilient member  506  has a spherical shape and the recessed cavity (not shown) in the second hole  511  also has a complementary spherical shape. In one embodiment, the first enlargement of the second elongate resilient member  506  has a cylindrical shape and the recessed cavity (not shown) in the second hole  511  also has a complementary cylindrical shape. In one embodiment, the first enlargement of the second elongate resilient member  506  has a polygonal shape and the recessed cavity (not shown) in the second hole  511  also has a complementary polygonal shape. 
     A first stop  521  is secured to the remote end  515  of the first support member  501 . The first stop  521  contains a first cavity  522  that captures and secures and the first elongate resilient member  505 . The first stop  521  may be secured to the first support member  501  by a snap button (not shown) or any other suitable means. 
     A second stop  523  is secured to the remote end of the second support member  502 . The second stop  523  contains a second cavity  524  that captures and secures and the second elongate resilient member  506 . The second stop  523  may be secured to the second support member  502  by a snap button (not shown) or any other suitable means. 
       FIG. 10  is a perspective right-view drawing illustrating an exemplary portable structure  500  that may be made using the bi-directional tensioning apparatus described herein. The right side of the portable structure  500  typically includes the second support member  502 , the third support member  525 , a third guide member  526 , a fourth guide member  527 , a third elongate resilient member  528 , and a fourth elongate resilient member  529 . The third guide member  526  includes a third coupler  530 , a fourth coupler  531 , and a third cylindrical tube  532 . The third cylindrical tube  532  has an outside and an inside diameter equal to that the first support member  501 . The third cylindrical tube  532  also contains a third hole  533  and a fourth hole  534  both extending perpendicular through the third cylindrical tube  532 . When the third cylindrical tube  532  is attached to the third coupler  530  and the fourth coupler  531 , the third hole  533  and the fourth hole  534  are oriented in the direction parallel to the second support member  502 . The third hole  533  will allow the third elongate resilient member  528  to pass through it up to the first enlargement. The fourth hole  534  will allow the fourth elongate resilient member  529  to pass through it up to the first enlargement. 
     One end of the third coupler  530  is rigidly secured to a base end of the second support member  502 , by adhesive or any other suitable means. One end of the fourth coupler  531  is rigidly secured to a base end of the third support member  525 , by adhesive or any other suitable means. A separate hole is formed in the cylindrical sidewall of each of the third coupler  530  and the fourth coupler  531 , proximate the end of the second support member  502  and the third support member  525 , respectively. Corresponding holes (not shown) are formed through the cylindrical sidewall of the third cylindrical tube  532  proximate the opposite ends thereof. Snap buttons, of the type known in the art, are inserted into the corresponding hole (not shown) on opposite ends of the third cylindrical tube  532 , so that the third snap button  535  and the fourth snap button  536  each protrude out of their respective holes. One end of the third cylindrical tube  532  is then inserted or “telescoped” into the third coupler  530  and arranged so that the third snap button  535  engages the hole through the sidewall thereof. The opposite end of the third cylindrical tube  532  then inserted or “telescoped” into the fourth coupler  531  and arranged so that the fourth snap button  536  engages the hole through the sidewall thereof. In this manner, the third cylindrical tube  532  is releasably connected to the second support member  502  and the third support member  525 . 
     The fourth guide member  527  includes a third snap-fit connector  537 , a fourth snap-fit connector  538 , and a fourth cylindrical tube  539 . An exemplary snap-fit connector is described herein below and shown in  FIGS. 13-14 . The fourth cylindrical tube  539  has outside and inside diameter equals to that the first support member  501  and the second support member  502 . 
     The third snap-fit connector  537  also contains a third keyhole  540  extending perpendicular through the third snap-fit connector  537 . The fourth snap-fit connector  538  also contains a fourth keyhole  541  also extending perpendicular through the fourth snap-fit connector  538 . When the fourth cylindrical tube  539  is attached to each of the third snap-fit connector  537  and the fourth snap-fit connector  538 , the third keyhole  540  and the fourth keyhole  541  are oriented in the direction parallel to the second support member  502 . The third keyhole  540  will allow the third elongate resilient member  528  to pass through it and to engage one of the spaced-apart enlargements (not shown). The fourth keyhole  541  will allow the fourth elongate resilient member  529  to pass through it and to engage one of the spaced-apart enlargements (not shown). Exemplary keyholes are described herein below and shown in  FIG. 13 . 
     The third snap-fit connector  537  typically fits on the second support member  502  adjacent to the second snap-fit connector  517  (see  FIG. 9 ). The second stop  523  is secured to the remote end of the second support member  502 . The second stop  523  contains the second cavity  524  that captures and secures the second elongate resilient member  506  and the third elongate resilient member  528 . 
     The third hole  533  may be of any shape that can allow the remote end of the third elongate resilient member  528  to pass through. In one embodiment, the third elongate resilient member  528  has a circular cross section and the third hole  533  has a circular shape. In another embodiment, the third elongate resilient member  528  has a polygonal cross section and the third hole  533  has the same polygonal shape. 
     In one embodiment, the third hole  533  has a surface recessed cavity (not shown) in a shape complementary to the shape of the first enlargement of the third elongate resilient member  528  to form a tight fit under pressure. 
     In one embodiment, the first enlargement of the third elongate resilient member  528  has a spherical shape and the recessed cavity (not shown) in the third hole  533  also has a complementary spherical shape. In one embodiment, the first enlargement of the third elongate resilient member  528  has a cylindrical shape and the recessed cavity (not shown) in the third hole  533  also has a complementary cylindrical shape. In one embodiment, the first enlargement of the third elongate resilient member  528  has a polygonal shape and the recessed cavity (not shown) in the third hole  533  also has a complementary polygonal shape. 
     The fourth hole  534  may be of any shape that can allow the remote end of the fourth elongate resilient member  529  to pass through. In one embodiment, the fourth elongate resilient member  529  has a circular cross section and the fourth hole  534  has a circular shape. In another embodiment, the fourth elongate resilient member  529  has a polygonal cross section and the fourth hole  534  has the same polygonal shape. 
     In one embodiment, the fourth hole  534  has a surface recessed cavity (not shown) in a shape complementary to the shape of the first enlargement of the fourth elongate resilient member  529  to form a tight fit under pressure. 
     In one embodiment, the rust enlargement of the fourth elongate resilient member  529  has a spherical shape and the recessed cavity (not shown) in the fourth hole  534  also has a complementary spherical shape. In one embodiment, the first enlargement of the fourth elongate resilient member  529  has a cylindrical shape and the recessed cavity (not shown) in the fourth hole  534  also has a complementary cylindrical shape. In one embodiment, the first enlargement of the fourth elongate resilient member  529  has a polygonal shape and the recessed cavity (not shown) in the fourth hole  534  also has a complementary polygonal shape. 
     A third stop  542  is secured to the remote end of the third support member  525 . The third stop  542  contains a third cavity  543  that captures and secures the fourth elongate resilient member  529 . The third stop  542  may be secured to the third support member  525  by a snap button (not shown) or any other suitable means. 
     In a similar fashion, the back-side (not shown) and the left side (not shown) of the exemplary portable structure  500  are constructed. 
       FIG. 11  is a top-view drawing illustrating an exemplary portable structure  500  that may be made using the bi-directional tensioning apparatus described herein. The portable structure  500  typically includes the first support member  501 , the second support member  502 , the third support member  525 , the fourth support member  554 , the first guide member  503 , the first elongate resilient member  505 , and the second elongate resilient member  506 , the second guide member  526 , the third elongate resilient member  528 , the fourth elongate resilient member  529 , the third guide member  544 , the fifth elongate resilient member  549 , the sixth elongate resilient member  551 , the fourth guide member  555 , the seventh elongate resilient member  557 , and the eighth elongate resilient member  559 . The first guide member  503  includes the first coupler  507 , the second coupler  508 , the first cylindrical tube  509 , the first snap button  512 , and the second snap button  513 . The second guide member  526  includes the third coupler  530 , the fourth coupler  531 , the second cylindrical tube  532 , the third snap button  535 , and the fourth snap button  536 . The third guide member  544  includes the fifth coupler  547 , the sixth coupler  553 , the third cylindrical tube  550 , the fifth snap button  548 , and the sixth snap button  552 . The seventh guide member  555  includes the seventh coupler  531 , the eighth coupler  561 , the cylindrical tube  558 , the seventh snap button  556 , and the eighth snap button  560 . 
       FIG. 12  is a bottom-view drawing illustrating an exemplary portable structure  500  that may be made using the bi-directional tensioning apparatus described herein. The portable structure  500  typically includes the first support member  501 , the second support member  502 , the third support member  525 , the fourth support member  554 , the second guide member  504 , the fourth guide member  527 , the sixth guide member  544 , and the eighth guide member  563 . The second guide member  504  includes the first snap-fit connector  516 , the second snap-fit connector  517 , the second cylindrical tube  518 , the first keyhole  519 , and the second keyhole  520 . The fourth guide member  527  includes the third snap-fit connector  537 , the fourth snap-fit connector  538 , the fourth cylindrical tube  539 , the third keyhole  550 , and the fourth keyhole  551 . The sixth guide member  544  includes the fifth snap-fit connector  564 , the sixth snap-fit connector  568 , the sixth cylindrical tube  566 , the fifth keyhole  565 , and the sixth keyhole  567 . The eighth guide member  563  includes the seventh snap-fit connector  571 , the eighth snap-fit connector  575 , the eighth cylindrical tube  573 , the seventh keyhole  572 , and the eighth keyhole  574 . 
     The bottom or remote end of the first support member  501  includes the first stop  521 , which contains the first cavity  522 . The bottom or remote end of the second support member  502  includes the second stop  523 , which contains the second cavity  524 . The bottom or remote end of the third support member  525  includes the third stop  542 , which contains the third cavity  543 . The bottom or remote end of the fourth support member  554  includes the fourth stop  569 , which contains the fourth cavity  570 . 
       FIG. 13  is a top-view drawing illustrating an exemplary snap-fit connector  600 , which includes a snap-fitting  601 , a cylindrical tube  602 , and a keyhole  603 . The snap-fitting  601  has an interior diameter slightly greater than the exterior diameter of the support member (not shown) so that it fits firmly into place with moderate pressure. The snap-fitting  601  is rigidly secured to the cylindrical tube  602  by adhesive or any other suitable means. The keyhole  603  includes a first hole  604  that is greater in thickness than the spaced-apart enlargements on the elongate resilient member (not shown), a second hole  605  that is less than the thickness of the spaced-apart enlargements on the elongate resilient member (not shown), and a key  606  that is greater than the thickness of the elongate resilient member, but less than the thickness of the spaced-apart enlargements on the elongate resilient member (not shown). Since a cylindrical tube  602  is used, the exact replica of the keyhole  603  is also made on the bottom-side of the cylindrical tube  602 . With the snap-fit connector  600 , the user inserts the remote end of the elongate resilient member (not shown) through the first hole  604  until the desired tension is achieved and one of the spaced-apart enlargements on the elongate resilient member (not shown) is contained within the cylindrical tube  602 , pushes the elongate resilient member (not shown) through the key  606  and secures it into the second hole  605 . 
     In another embodiment, the orientation of the keyhole  603  is reversed from the orientation shown in  FIG. 13 . In another embodiment, the orientation of the keyhole  603  is perpendicular to the length of the cylindrical tube  602  shown in  FIG. 13 . In another embodiment, the orientation of the keyhole  603  is at an angle not perpendicular nor parallel to the length of the cylindrical tube  602  shown in  FIG. 13 . 
     In another embodiment, the keyhole does not include the key  606 . In that embodiment, the user inserts the remote end of the elongate resilient member (not shown) through the first hole  604  until the desired tension is achieved and one of the spaced-apart enlargements on the elongate resilient member (not shown) is contained within the cylindrical tube  602 , pushes the elongate resilient member (not shown) directly into the second hole  605 . 
       FIG. 14  is a right side-view drawing illustrating an exemplary snap-fit connector  600  that illustrates the relationship between the snap-fitting  601  and cylindrical tube  602 . The keyhole  603  is not shown. 
       FIG. 15  is a perspective front-view drawing illustrating an exemplary bi-directional tensioning apparatus  700 : The bi-directional tensioning apparatus  700  typically includes a first support member  701 , a second support member  702 , a first guide member  703 , a second guide member  704 , and an elongate resilient member  705 . The first guide member  703  includes a first coupler  706 , a second coupler  707 , and a cylindrical tube  708 . The cylindrical tube  708  has outside and inside diameters equals to that the first support member  701 . The cylindrical tube  708  also contains a first hole  711  extending perpendicular through the cylindrical tube  708 . When the cylindrical tube  708  is attached to the first coupler  706  and the second coupler  707 , the first hole  711  is oriented in the direction parallel to the support member  701 . The first hole  711  will allow the elongate resilient member  705  to pass through it up to the first enlargement. One end of the first coupler  706  is rigidly secured to a base end of the first support member  701 , by adhesive or any other suitable means. One end of the second coupler  707  is rigidly secured to a base end of the second support member  702 , by adhesive or any other suitable means. A separate hole (not shown) is formed in the cylindrical sidewall of each of the couplers  706  and  707 , proximate the end of the two support members  701  and  702 . Corresponding holes (not shown) are formed through the cylindrical sidewall of the cylindrical tube  708  proximate each end thereof. Snap buttons, of the type known in the art, are inserted into the corresponding holes (not shown) on both ends of the cylindrical tube  708 , so that the first snap button  709  and the second snap button  710  each protrude out of their respective holes. One end of the cylindrical tube  708  is then inserted or “telescoped” into the first coupler  706  and arranged so that the first snap button  709  engages the hole through the sidewall thereof. One end of the cylindrical tube  708  is then inserted or “telescoped” into the second coupler  707  and arranged so that the second snap button  710  engages the hole through the sidewall thereof. In this manner, the cylindrical tube  708  is releasably connected to the first and second support members  701  and  702 . The first support member  701  extends linearly from its base end  712  to a remote end  713 . 
     The second guide member  704  is releasably attached to the first support member  701  and the second support member  702  with two snap buttons (not shown). The second guide member  704  also contains a first keyhole  715  extending perpendicular through the second guide member  704 . The first keyhole  715  will allow the elongate resilient member  705  to pass through it and to engage one of the spaced-apart enlargements (not shown). 
     Exemplary keyholes are described herein below and shown in  FIG. 13  above. 
     The first hole  711  may be of any shape that can allow the remote end of the elongate resilient member  705  to pass through. In one embodiment, the elongate resilient member  705  has a circular cross section and the first hole  711  has a circular shape. In another embodiment, the first elongate resilient member  705  has a polygonal cross section and the first hole  711  has the same polygonal shape. 
     In one embodiment, the first hole  711  has a surface recessed cavity (not shown) in a shape complementary to the shape of the first enlargement of the elongate resilient member  705  to form a tight fit under pressure. 
     In one embodiment, the first enlargement of the elongate resilient member  705  has a spherical shape and the recessed cavity (not shown) in the first hole  711  also has a complementary spherical shape. In one embodiment, the first enlargement of the elongate resilient member  705  has a cylindrical shape and the recessed cavity (not shown) in the first hole  711  also has a complementary cylindrical shape. In one embodiment, the first enlargement of the elongate resilient member  705  has a polygonal shape and the recessed cavity (not shown) in the first hole  711  also has a complementary polygonal shape. 
     The second hole  715  may be of any shape that can allow the remote end of the elongate resilient member  705  to pass through. In one embodiment, the elongate resilient member  705  has a circular cross section and the second hole  715  has a circular shape. In another embodiment, the elongate resilient member  705  has a polygonal cross section and the second hole  715  has the same polygonal shape. 
     In one embodiment, the second hole  715  has a surface recessed cavity (not shown) in a shape complementary to the shape of an enlargement of the elongate resilient member  705  to form a tight fit under pressure. 
     The coupler  714  contains a keyhole (not shown) extending perpendicular thereof. The keyhole (not shown) will allow the elongate resilient member  705  to pass through it and to engage one of the spaced-apart enlargements (not shown). Exemplary keyholes are described herein below and shown in  FIG. 13  above. The coupler  714  may be linked via connection  716  to a pulley system (not shown) to a user (not shown) to allow the bi-directional tensioning apparatus  700  to function as a resistance system commonly found in a Universal Gym (BMI Karts &amp; Supply, Versailles, Ohio, 45380), without the need for heavy weights. 
       FIG. 16  is a front-view drawing illustrating an exemplary resilient member  800 . The resilient member  800  having a base end  801  and a remote end  802 . The resilient member  800  includes a resilient material  803  and holes  804  along the length of the resilient member  800 . 
     In one embodiment, the resilient member  800  may be made of, for example, a styrene-butadiene rubber or a chloroprene (i.e., neoprene) rubber. The resilient member  800  has excellent memory characteristics and returns to its original shape after numerous elongations. 
     The resilient member  800  may be also be made of any other suitable elastic material, for example, natural rubber, synthetic polyisoprene, butyl rubber (copolymer of isobutylene and isoprene), halogenated butyl rubber, polybutadiene, nitrile butadiene rubber, hydrogenated nitrile rubber, ethylene propylene rubber, epichlorohydrin rubber, polyacrylic rubber, silicone rubber, fluorosilicon rubber, fluoroelastomers, prefluoroelastomers, thermoplastic polyurethane, polyether block amides, chlorosulfonated polyethylene, ethylene-vinyl acetate, and the like, or combinations thereof. 
     Typical physical properties for a suitable elastic material includes, for example, a polymer specific gravity from about 0.8 to about 2.0, a tensile strength (in pounds per square inch) from about 1000 to about 9000, and a percentage elongation to about 900. The elastic material should also possess, for example, good abrasion resistance, good tear resistance, and good ozone resistance. 
     In one embodiment, the resilient member  800  may include an enlargement (not shown) at the base end  801 . The enlargement (not shown) may be, for example, of any shape that prevents the resilient member  800  from sliding through one of the first guide members described herein. The enlargement (not shown) may be, for example, a cylindrical shape, a spherical shape, a square shape, a polygonal shape, and the like. Preferably, the enlargement (not shown) has a cylindrical shape. More preferably, the enlargement (not shown) has a cylindrical shape with a bevel edge on the side of the enlargement (not shown) opposite the first guide member to provide reinforcement. 
       FIG. 17  is a perspective front-view drawing illustrating an exemplary bi-directional tensioning apparatus  900 . The bi-directional tensioning apparatus  900  typically includes a support member  901 , a first guide member  902 , a second guide member  903 , and elongate resilient member  904 . The first guide member  902  includes a first coupler  905  and a first cylindrical tube  906 . The first cylindrical tube  906  has an outside and an inside diameters equal to that the support member  901 . The first cylindrical tube  906  also contains a first hole  907  extending perpendicular through the first cylindrical tube  906 . When the first cylindrical tube  906  is attached to the first coupler  905 , the first hole  907  is oriented in the direction parallel to the support member  901 . The first hole  907  will allow the elongate resilient member  904  to pass through it and be connecter with the compression pin (not shown). 
     One end of the first coupler  905  is rigidly secured to a base end of the support member  901 , by adhesive or any other suitable means. A separate hole (not shown) is formed in the cylindrical sidewall of the first coupler  905 , proximate the end of the support member  901 . A corresponding hole (not shown) is formed through the cylindrical sidewall of the first cylindrical tube  906  proximate the end thereof. A snap button, of the type known in the art, is inserted into the corresponding hole (not shown) on one end of the first cylindrical tube  906 , so that the first snap button  908  protrudes out of the hole. One end of the first cylindrical tube  906  is then inserted or “telescoped” into the first coupler  905  and arranged so that the first snap button  908  engages the hole through the sidewall thereof. In this manner, the first cylindrical tube  906  is releasably connected to the support member  901 . The support member  901  extends linearly from its base end  909  to a remote end  910 . The second guide member  903  includes the second coupler  911  and the second cylindrical tube  912 . The second coupler  911  may be a snap-fit connector. An exemplary snap-fit connector is described herein below and shown in  FIG. 18 . 
     The second cylindrical tube  912  has an outside and an inside diameter equal to that the support member  901 . A corresponding hole (not shown) is formed through the cylindrical sidewall of the second cylindrical tube  912  proximate the end thereof. A snap button, of the type known in the art, is inserted into one end of the second cylindrical tube  912 , so that the second snap button  913  protrudes out of the hole. One end of the second cylindrical tube  912  is then inserted or “telescoped” into the second coupler  911  and arranged so that the second snap button  913  engages the hole through the sidewall thereof. In this manner, the second cylindrical tube  912  is releasably connected to the support member  901 . The second cylindrical tube  912  also contains a connector  914  also extending perpendicular through the second cylindrical tube  912 . When the second cylindrical tube  912  is attached to the second coupler  911 , the connector  914  is oriented in the direction parallel to the support member  901 . The connector  914  will allow the first elongate resilient member  904  to pass through it and to engage one of the holes (not shown). Exemplary connectors are described herein below and shown in  FIG. 18 . 
     A connector  915  is secured to the remote end  910  of the support member  901 . The connector  915  captures one of the holes and secures the elongate resilient member  904 . In one embodiment, the second guide member  903  includes the second coupler  911  and the second cylindrical tube  912 . In another embodiment, the second guide member  903  is a second cylindrical tube (not shown) with a coupler end. 
       FIG. 18  is a top-view drawing illustrating an exemplary snap-fit connector  1000 , which includes a snap-fitting  1001 , a cylindrical tube  1002 , and a connector  1003 . The snap-fitting  1001  has an interior diameter slightly greater than the exterior diameter of the support member (not shown) so that it fits firmly into place with moderate pressure. The snap-fitting  1001  is rigidly secured to the cylindrical tube  1002  by adhesive or any other suitable means. The connector  1003  includes a hole  1004 . Since a cylindrical tube  1002  is used, the exact replica of the connector  1003  is also made on the bottom-side of the cylindrical tube  1002 . With the snap-fit connector  1000 , the user inserts the remote end of the elongate resilient member (not shown) through the hole  1004  until the desired tension is achieved and one of the holes on the elongate resilient member (not shown) is contained within the cylindrical tube  1002 , pushes the hole in the elongate resilient member (not shown) through the pin  1005  and secures it. The pin  1005  is held in position by the compression spring  1006  located within the cylindrical tube  1002 . 
     In another embodiment, the orientation of the connector  1003  is reversed from the orientation shown in  FIG. 18 . In another embodiment, the orientation of the connector  1003  is perpendicular to the length of the cylindrical tube  1002  shown in  FIG. 18 . In another embodiment, the orientation of the connector  1003  is at an angle not perpendicular nor parallel to the length of the cylindrical tube  1002  shown in  FIG. 18 . 
       FIG. 19  is a block diagram illustrating an exemplary method of assembling an exemplary bi-directional tensioning device  1100 . The method  1100  includes: connecting the one or more first guide members to base end or proximate the base end of each of the one or more support members; connecting the one or more optional second guide members to the one or more support members at a position intermediate the base end and the remote end of the one or more support members; passing the remote ends of each of the one or more elongate resilient members through the first hole extending through the one or more first guide members toward the remote end of the one or more support members and securing each first enlargement; and passing the remote ends of each of the one or more elongate resilient members through the first hole extending through the one or more optional second guide members toward the remote end of the one or more support members; and securing one of the spaced-apart enlargements on the one or more optional second guide members. 
     The present invention also provides various portable structures by slightly modifying the components of the exemplary bi-directional tensioning apparatus  400  (see  FIG. 6 ). For example, if four three-way 90 degree couplers are substituted for each of the two couplers  407  and  408  that would be found in two bi-directional tensioning apparatuses  400 , the two modified bi-directional tensioning apparatuses can be linked together by a third and a fourth first guide members and a third and a fourth second guide members to provide a box-type portable structure. Likewise, a three-sided structure may be formed using three support members, each having a three-way 60-degree coupler, with three first guide members and three second guide members. In a similar fashion, a five-sided, a six-sided, a seven-sided, an eight-multi-sided structure can be formed by varying the angle on the three-way couplers. 
     The present invention also provides various fence structures by slightly modifying the components of the exemplary bi-directional tensioning apparatus  400 . For example, a fence structure may be formed using three support members, two having two-way 90-degree couples and the third having a three-way 180 degree coupler, with three first guide members and three second guide members. 
     In the claims provided herein, the steps specified to be taken in a claimed method or process may be carried out in any order without departing from the principles of the invention, except when a temporal or operational sequence is explicitly defined by claim language. Recitation in a claim to the effect that first a step is performed then several other steps are performed shall be taken to mean that the first step is performed before any of the other steps, but the other steps may be performed in any sequence unless a sequence is further specified within the other steps. For example, claim elements that recite “first A, then B, C, and D, and lastly E” shall be construed to mean step A must be first, step E must be last, but steps B, C, and D may be carried out in any sequence between steps A and E and the process of that sequence will still fall within the four corners of the claim. 
     Furthermore, in the claims provided herein, specified steps may be carried out concurrently unless explicit claim language requires that they be carried out separately or as parts of different processing operations. For example, a claimed step of doing X and a claimed step of doing Y may be conducted simultaneously within a single operation, and the resulting process will be covered by the claim. Thus, a step of doing X, a step of doing Y, and a step of doing Z may be conducted simultaneously within a single process step, or in two separate process steps, or in three separate process steps, and that process will still fall within the four corners of a claim that recites those three steps. 
     Similarly, except as explicitly required by claim language, a single substance or component may meet more than a single functional requirement, provided that the single substance fulfills the more than one functional requirement as specified by claim language. 
     All patents, patent applications, publications, scientific articles, web sites, and other documents and materials referenced or mentioned herein are indicative of the levels of skill of those skilled in the art to which the invention pertains, and each such referenced document and material is hereby incorporated by reference to the same extent as if it had been incorporated by reference in its entirety individually or set forth herein in its entirety. Additionally, all claims in this application, and all priority applications, including but not limited to original claims, are hereby incorporated in their entirety into, and form a part of, the written description of the invention. Applicants reserve the right to physically incorporate into this specification any and all materials and information from any such patents, applications, publications, scientific articles, web sites, electronically available information, and other referenced materials or documents. Applicants reserve the right to physically incorporate into any part of this document, including any part of the written description, the claims referred to above including but not limited to any original claims.