Patent Publication Number: US-2023158724-A1

Title: Hand-held three-dimensional drawing device

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to and the benefit of U.S. Provisional App. No. 63/282,684, filed on Nov. 23, 2021, the entirety of which is incorporated hereinby reference. 
    
    
     BACKGROUND 
     Field 
     The present disclosure relates to extrusion devices and, in particular, a hand-held implement configured to extrude a material so as to construct three-dimensional (3D) objects. 
     Description of the Related Art 
     Various devices have been developed that allow a user to incorporate specific designs and artwork into food creations. Some devices allow a user to decorate cakes and cookies with icing. Other devices allow a user to melt sugar and pour the molten material into molds or other substrates. These devices generally give the user some control over how the material is dispensed, with some being in the form of a gun having a trigger for driving material toward the dispensing tip. 
     These devices have found some application and appealed to various users. However, broad adoption has been limited due to certain limitations and drawbacks associated with these devices. 
     SUMMARY 
     The present disclosure describes drawing devices and methods that can allow users to create unique designs and workpieces using a variety of different materials. Further, the present disclosure also describes aspects of drawing devices and methods that allow for quick reloading and maintenance of the device in order to permit users to more easily focus on the artwork rather than the tool through which the artwork is being created. 
     In accordance with some embodiments disclosed herein is the realization that as projects become more complex with other external factors that demand the user&#39;s attention, the drawing device should provide a simple, dependable, customizable, and long-lasting material distribution or flow so that the user can focus on critical aspects of the project itself. For example, in the food industry, a pâtissier can use embodiments of the drawing device to adorn their products, but must be aware of other factors, such as the balance, consistency, or temperature of the substrate or delicacy, as well as other aspects of their project, which are all time sensitive and require exacting attention to detail. 
     Some embodiments of the present disclosure describe a hand-held drawing device that allows a user to “draw” a 2D or 3D structure and to easily refill or replace the material or feed stock. Optionally, some embodiments can be configured such that the drawing devices or methods can be used to transform materials, such as sugar, gummy, or other edible materials, into artistic creations for adorning food or drink items. Until now, the use of certain materials in the manner described herein has been limited based on several factors. 
     For example, in accordance with an aspect of some embodiments is the realization that the use of sugar in a transformational manner is difficult due to various challenges, including the difficulty of melting and handling sugar in such apparatuses, advancing molten sugar over a meaningful distance, and providing a reliable and useful extruding tool, to name a few. 
     Further, in accordance with an aspect of some embodiments is the realization that melting and extruding a material, such as sugar, can present substantial difficulty due to the challenging properties of molten sugar and its handling, which may include stickiness, quick hardening, as well as overheating or burning of the material. In developing the concepts and disclosure presented herein, Applicant discovered the challenge of successfully pushing sugar across a certain distance, and how difficult such a process is. 
     Furthermore, other challenges arose, such as being able to successfully and rapidly replace and/or reload material into the device so that the continuity of creation is uninterrupted. Moreover, Applicant also realized the challenge of making the device and process accessible to an artist by ensuring a comfortable, easy-to-hold device that could be manipulated like a pen. 
     With these and other challenges in mind, Applicant developed the presently disclosed devices and methods and has accessed a new market in the cool and airy industry that will allow for masterful, detailed art to be incorporated into food and drink products on a professional and household scale. These and other advancements represent a substantial new product segment, for which Applicant has received enthusiastic feedback and expects incredible results for its business. 
     Accordingly, some embodiments can provide a handheld drawing device that comprises a housing, a nozzle assembly, and a loading mechanism. The housing can have an internal volume, a longitudinal axis, and a port that permits access to the internal volume of the housing. 
     The loading mechanism can position or drive material toward the nozzle assembly for extrusion therefrom. The loading mechanism can comprise an advancement mechanism to drive the material toward the nozzle assembly. The loading mechanism can optionally comprise a cartridge that supports or carries material and that can be releasably coupled to the housing. 
     In some embodiments, the cartridge can be is removably insertable into the port of the housing and have a rotation axis and a plurality of chambers disposed thereabout. Each of the plurality of chambers can be configured to support a pellet of material therein and be rotatable about the rotation axis to selectively position an active chamber of the plurality of chambers in alignment with the longitudinal axis at an active position. 
     Once in position, the material disposed in the active chamber can be advanced toward the nozzle assembly. The nozzle assembly can be coupled to the device and comprise an exit nozzle and a heating element that can facilitate melting and extrusion of the material from the device. 
     In some embodiments, the device can further comprise a pushrod disposed within the housing and translatable along the longitudinal axis. The pushrod can be movable into the active chamber toward an extended position for driving the pellet out of the active chamber toward the heating element for melting the pellet and extruding the material. 
     The pushrod can be driven by a motor, a type of spring (coil or leaf), user-applied force, or other driving mechanism to cause movement of the pushrod into and/or away from the extended position. Thus, some embodiments do not use a motor for operation. 
     For example, the device can comprise an advancing mechanism that drives movement of the material out of the active chamber toward the nozzle assembly. The advancing mechanism can perform manual (e.g., completed via manual input of a kinetic energy or storing of potential energy, such as into a spring, compressed fluid/air, or otherwise) or motorized movement of components. Such manual movement can be performed by directly advancing the pushrod by pushing on the pushrod (linear drive), pulling back on the pushrod to preload a spring coupled to the pushrod and then permitting the spring to exert a linear force on the pushrod (linear drive), rotation of a thumb wheel to advance the pushrod (rotary movement about or transverse relative to a longitudinal axis of the device), or combinations of such linear and rotary movement Thus, some embodiments do not use a motor, but instead use a manually inputted driving force, such as a type of spring (coil or leaf), user-applied force, or other driving mechanism. 
     In some embodiments, the advancing mechanism of the device can comprise a motor, a type of spring (coil or leaf), user-applied force, or other driving mechanism that is coupled to the device. The driving mechanism can be configured to drive motion of the pushrod to the extended position. Further, the device can optionally comprise one or more actuators coupled to the device. The actuator(s) can be configured to activate the driving mechanism and control movement of the pushrod. The user can thereby extrude the pellet from the exit nozzle. 
     Additionally, some embodiments can comprise a retraction mechanism whereby the pushrod can be urged toward the retracted position from the extended position. The pushrod can be manually or automatically urged toward the retracted position from the extended position. 
     Optionally, the device can comprise a reloader mechanism that facilitates loading of material into the device. For example, the reloader mechanism can comprise a screw drive mechanism, a pushrod mechanism, a clip mechanism, a belt mechanism, and/or a wave drive mechanism. The reloader mechanism can utilize one or more material loading components, such as hoppers, cartridges, clips, and/or belts that can be used in accordance with some embodiments to provide a quick and simple manner of achieving steady or continuous usage of the device, with minimal interruption to the user. 
     These and other features can advantageously allow the user to focus more on the actual work being performed using the device rather than getting the device to work properly. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are included to provide further understanding and are incorporated in and constitute a part of this specification, illustrate disclosed embodiments and together with the description serve to explain the principles of the disclosed embodiments. In the drawings: 
         FIG.  1    is a perspective view of a cartridge-type drawing device, according to some embodiments. 
         FIG.  2    is a bottom perspective view of the drawing device shown in  FIG.  1   , with a cartridge assembly separated from a body of the drawing device, according to some embodiments. 
         FIG.  3    is a bottom perspective view showing aspects of a docking receptacle of the drawing device shown in  FIG.  1   , according to some embodiments. 
         FIG.  4    is a perspective view of a cartridge assembly for use with the drawing device  FIG.  1   , according to some embodiments. 
         FIG.  5    is a perspective, cross-sectional view of the cartridge assembly of  FIG.  4   . 
         FIG.  6    is an exploded view of the cartridge assembly of  FIG.  4   . 
         FIGS.  7  and  8    are perspective views of a drawing device in which the housing has been removed to illustrate internal components thereof, according to some embodiments. 
         FIGS.  9  and  10    are side, cross-sectional views of a drawing device showing extended and retracted positions of a pushrod, according to some embodiments. 
         FIGS.  11  and  12    are side views of a drawing device, wherein the housing has been removed for illustrating internal components thereof, showing extended and retracted positions of the pushrod, according to some embodiments. 
         FIGS.  13 A and  13 B  are side cross-sectional views of a cartridge-type drawing device, according to some embodiments. 
         FIG.  14    is a side, cross-sectional view of a cartridge-type drawing device that utilizes a spring-type discharge driver for the cartridge, according to some embodiments. 
         FIG.  15    is a side, cross-sectional view of a cartridge-type drawing device that utilizes a belt-type discharge driver for the cartridge, according to some embodiments. 
         FIG.  16    is a side, cross-sectional view of a drawing device having a screw-drive-type discharge driver, according to some embodiments. 
         FIGS.  17 A and  17 B  are side, cross-sectional views of a drawing device having a pusher-type discharge driver, according to some embodiments. 
         FIG.  18    is a side, cross-sectional view of a drawing device having a wave-generator-type discharge driver, according to some embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     The detailed description set forth below is intended as a description of various configurations of the subject technology and is not intended to represent the only configurations in which the subject technology may be practiced. The appended drawings are incorporated herein and constitute a part of the detailed description. The detailed description includes specific details for the purpose of providing a thorough understanding of the subject technology. However, it will be apparent to those skilled in the art that the subject technology may be practiced without these specific details. In some instances, well-known structures and components are shown in block diagram form in order to avoid obscuring the concepts of the subject technology . Like components are labeled with identical element numbers for ease of understanding. 
     The present disclosure describes various features of a hand-held drawing device that can comprise a three-dimensional drawing pen having a housing, a nozzle assembly, and a loading mechanism. The loading mechanism can advantageously facilitate use of the 3D drawing pen, for example, by providing a substantial or semi-continuous supply of material to the nozzle assembly for extrusion and artistic creation. 
     The loading mechanism can comprise an advancement mechanism to drive the material toward the nozzle assembly. 
     The loading mechanism can optionally comprise a cartridge that supports or carries material for use by the 3D pen. The cartridge can be releasably coupled to the housing of the 3D pen. 
     In some embodiments, the loading mechanism can also optionally comprise a reloading mechanism that repositions material to an active position and for driving the material toward the nozzle assembly. 
     Various embodiments of loading mechanisms, including cartridge-type and non-cartridge-type loading mechanisms, along with various advancement and reloading mechanisms are discussed and illustrated herein. These and other features can be individually modified or implemented into one or more embodiments of the drawing pen disclosed herein. 
     Accordingly, features illustrated in the figures may be interchangeably incorporated into a given embodiment, as discussed and shown herein. 
     Referring now to the figures, various aspects of an embodiment of the present disclosure are illustrated in  FIGS.  1 - 18   .  FIG.  1    is a front perspective view of a hand-held extrusion apparatus or drawing device  10  in accordance with some embodiments of the present disclosure. As illustrated, the drawing device  10  can comprise an elongate housing  12  that can be sized and configured to fit in a user&#39;s hand and suitably shaped to allow for manipulation like a writing instrument, such as a pen or pencil. The drawing device  10  can comprise one, two, three, or more actuators  14 . The actuator  14  can be in the form of one or more buttons  16 , which can be positioned along the housing at a location that allows the user to press or move the actuator  14 , thereby activating one or more functions of the drawing device  10 . Although the actuator  14  is illustrated as a series of buttons  16 , the actuator  14  can comprise other functional components, such as switches, sliders, or other such features known in the art. 
     The drawing device  10  can also comprise a nozzle assembly  20  and a loading mechanism  21 . The nozzle assembly  20  can be positioned at a distal end portion of the drawing device  10 . The user can manipulate the drawing device  10  by gripping the housing  12  proximal to the distal end portion  22  along a central portion  24  and a proximal end portion  26 . 
     Referring now to  FIG.  2   , the drawing device  10  is shown in a bottom perspective view to illustrate how the drawing device  10  can be loaded with material. The drawing device  10  can comprise a loading mechanism that can include a removable cartridge assembly  30 . The removable cartridge assembly  30  can be inserted into and attached to the drawing device  10 . Advantageously, the cartridge assembly  30  can support material, in the form of one or more pellets  32 , adjacent to the nozzle assembly  20 , thereby enabling the material  32  to be advanced toward the nozzle assembly  20  along a short or minimal distance. The pellets  32  can be oblong or round in shape, for example, in the shape of a stick of material. As noted above, the length of travel of material has been identified as one of the significant challenges in developing a reliable, user-friendly drawing device that does not clog or become cumbersome in use. The cartridge assembly  30  and its placement and loading onto the drawing device  10  and the illustrated embodiment advantageously provide a robust and innovative approach for at least the reasons that the material  32  can be quickly loaded and driven out of the cartridge assembly  30  during use of the drawing device  10 . 
     As illustrated in  FIG.  3   , a push rod  40  of the drawing device  10  can be used to advance or urge material residing in the cartridge assembly  30  toward the nozzle assembly  20 . As the material enters the nozzle assembly  20 , the material can be melted and extruded out of the exit nozzle  50 . After the push rod  40  has completed its full cycle, the cartridge assembly  30  can rotate to permit another chamber of the cartridge assembly  32  be aligned with the push rod  40  so that the user can activate the push rod  40  to drive additional material through the drawing device  10  in order to thereby extruded from the exit nozzle  50 . 
     The cartridge assembly  30  and its operation, as illustrated in  FIGS.  2  and  3   , is shown in greater detail in  FIGS.  4 - 6   . As shown, the cartridge assembly  30  can comprise a cartridge  60 , a rotational shaft  62 , a mounting component,  64 , and a buckle cover  66 . 
       FIG.  4    illustrates an embodiment of the cartridge assembly in an assembled state. As shown, the cartridge  60  can be received within the mounting component  64  and coupled to the buckle cover  66 . The rotational shaft  62  can define a first end  70  that extends into a rotational aperture  72 , as shown in  FIG.  5   . The rotational engagement between the rotational aperture  72  and the first end  70  of the rotational shaft  62 , as well as the rotational coupling between the rotational shaft  62  and a central bore  74  of the cartridge  60 , can enable the cartridge  60  to be positioned in a mounted configuration. In the mounted configuration, as shown in  FIG.  5   , the cartridge  60  can freely rotate about a cartridge axis  78 . Further, the mounting component  64  can at least partially receive an end portion  90  of the cartridge  60  within an engagement cavity  92  of the mounting component  64 . In some embodiments, the engagement cavity  92  can comprise a cylindrical recess that extends longitudinally along a central axis of the mounting component. The engagement cavity  92  can be configured to be coaxially aligned with the cartridge axis  78  in order to permit the cartridge  60  to be at least partially received within the engagement cavity  92  of the mounting component  64 . 
     Additionally, in accordance with some embodiments, the mounting component  64  can optionally comprise one or more engagement members  100  that can mate with one or more respective engagement members  102  of the buckle cover  66 , as illustrated in  FIGS.  3 ,  4 , and  6   . In accordance with some embodiments, the engagement members  100  of the mounting component  64  can comprise one or more protrusions. The protrusions can have cross-sectional profiles that can mate, interact, or engage with corresponding cavity or recess features of the engagement members  102  of the buckle cover  66 . 
     As illustrated in the embodiment shown in  FIGS.  3 - 6   , the engagement members  100  of the mounting component  64  can slide into engagement with recesses of the engagement members  102  of the buckle cover  66 . The engagement members  100  can comprise a T-shaped cross-section that is configured to follow and match a shape of an exterior surface  104  of the buckle cover  66 . As illustrated in  FIG.  4   , the engagement members  100 ,  102  can help collectively form or provide a smooth, continuous outer surface of the drawing device  10  that allows the user to not only have a desirable ergonomic, easy-to-grasp contour or profile for the drawing device  10 , but advantageously also permits the user quick and easy visual or tactile verification that the mounting component  64  is positioned within the drawing device  10 . Such embodiments can provide a manner for verifying the presence of the cartridge  60  and mounting component  64 , providing at least a hint or reminder to the user that at least the cartridge  60 , and perhaps the material  32  for use in the drawing device  10 , may not be present or loaded into the drawing device  10 . 
     The embodiment illustrated in  FIGS.  4 - 6    of the cartridge assembly  30  also illustrates that the buckle cover  66  can comprise a cartridge cavity or receptacle  110  into which the cartridge  60  can be received, as illustrated in  FIGS.  4  and  5   . The cartridge receptacle can comprise one or more rib members  112  that provide a support against which the cartridge  60  can be contacted for facilitating the positioning and rotation of the cartridge  60  within the cartridge receptacle  110 . Additionally, the buckle cover  66  can comprise a receptacle mounting wall or bracket  114  through which the rotational aperture  72  can extend and whereagainst the cartridge  60  can be positioned in the loaded configuration. Additionally, the mounting bracket can comprise a discharge aperture  120 , axially spaced apart from the rotational aperture  72  and the cartridge axis  78 , in order to permit material positioned within the cartridge  60  to pass through the discharge aperture  120  toward the nozzle assembly  20 . 
     Optionally, the buckle cover  66  can also comprise one or more coupling members  130 . The coupling members can be positioned adjacent to and interface between the buckle cover  66  and the housing  12  of the drawing device  10 . The coupling members can mechanically, magnetically, or otherwise engage or mate with respective coupling members  132  of the housing  12 . Referring again to  FIG.  3   , the drawing device  10  can comprise a docking receptacle  140 , wherein the cartridge assembly  30  can be received. The coupling members  132  of the housing can be positioned adjacent to or within the docking receptacle  140 . As illustrated in 
       FIGS.  2  and  3   , the coupling members  132  can extend from the housing into the docking receptacle  140 . The respective coupling members  130  of the buckle cover  66  can engage with the coupling members  132  disposed within the docking receptacle  140 . Thus, when the cartridge assembly  30  is positioned within the docking receptacle  140 , the engagement between the coupling members  130 ,  132  can ensure that the cartridge assembly  30  remains engaged with the housing  12  of the drawing device  10  and does not become accidentally dislodged or separated from the drawing device  10 . 
     In some embodiments, the coupling members  130 ,  132  can comprise one or more magnets that attract to each other, respectively, thus making the cartridge assembly easy to couple to the drawing device  10 , while securely engaging the cartridge assembly  30  in the loaded position. Moreover, with sufficient, intentional exertion by the user, the cartridge assembly  30  can be removed. For example, the cartridge assembly  30  can be removed from the docking receptacle  140  by positioning the user&#39;s fingers into or underneath the disengagement recesses  142  and separating the cartridge assembly  30  from the docking receptacle  140 . The disengagement recesses  142  can be located along a perimeter of the docking receptacle  140 . An embodiment of the disengagement recesses  142  and the docking receptacle  140 , along with the protruding coupling members  132  is illustrated in  FIG.  3   . 
     Optionally, the coupling members  130  can be correspondingly recessed into the buckle cover  66 , thereby providing both a magnetic attraction, as well as a mechanical engagement between the buckle cover  66  and the docking receptacle  140  that limits one or more degrees of freedom of movement of the buckle cover  66  relative to the docking receptacle  140  when the cartridge assembly  30  is received and coupled to the docking receptacle  140 . 
     In some embodiments, the cartridge assembly  30  can be configured as a rotatable component having a plurality of chambers that can each be loaded with one or more pellets  32  of material  32 . For example, referring to  FIGS.  4 - 6   . The cartridge can comprise one or more chambers  150 . The embodiment illustrated in these figures has five chambers, but other embodiments can be developed that have two, three, four, six, or more chambers. In accordance with some embodiments, the cartridge  60  may advantageously comprise at least two chambers  150  in order to allow the user to operate the drawing device  10  over a series of cycles and/or to allow the user to load and dispense different types of materials from the drawing device  10 . 
     In accordance with some embodiments, the chambers  150  of the cartridge  60  can have a cylindrical shape that allows the material to be loaded thereunto. Additionally, the chambers  150  can be symmetrically and/or evenly spaced about the cartridge axis  78 . Such alignment can facilitate that each of the chambers  150  be rotatable into axial alignment with the discharge aperture  120  of the buckle cover  66 . In this regard, the discharge aperture  120  may be sized to be at least equal to the cross-sectional profile or dimension of each of the chambers  150  in order to permit the material  32  to be driven through the discharge aperture  120 . As will be discussed further below, during operation of the drawing device  10 , each of the chambers  150  can successively be rotated about the cartridge axis  78  and the material  32  disposed within the chambers  150  can be driven out of the chambers  150 , through the discharge aperture  120 , and into the nozzle assembly  20  where the material  32  is melted and extruded out of the exit nozzle  50 . 
     The modular nature of the cartridge assembly  30  and the docking receptacle  140  can provide numerous advantages and benefits that have hitherto been unavailable for a device intended to utilize distinct materials, such as sugar, gummy, plastics, or other such materials. The modularity and ease of loading, including both the disassembly and assembly of the components illustrated and described herein, allows a user to quickly remove the cartridge assembly  30 , load it with a desired array of materials (e.g., pellets  32 ), and immediately couple the cartridge assembly  30  to the drawing device  10  for use. The facility of disassembly of some embodiments also enables a user to clean and/or replace components, as needed, for maintenance of the device. 
     The modularity of the drawing device  10  also advantageously allows quick disassembly, cleaning, and assembly of the drawing device  10 . Applicant has found that the provision of multiple cartridge assemblies can also allow the user to have substantial uninterrupted and dedicated time using the drawing device  10  with only minimal pauses to change out the cartridge assembly. 
     These and other advantages of the presently disclosed drawing device have not been possible using other conventional devices. Other attempts to create viable drawing pens have failed due to the poor design, slow operation, slow loading, and other problematic aspects of prior art devices, and have not necessarily even contemplated the challenges and developments presented in accordance with some embodiments disclosed herein. Indeed, in contrast to those conventional devices, the present disclosure provides a drawing device that can advantageously be loaded or unloaded quickly, has a simple and robust assembly of components, and requires a minimal material travel distance during the extrusion process. These, among other advantages, create a reliable, commercially significant product that will enable the creation of culinary and other works of art that by providing a reliable and free, uninterrupted workflow and creativity, as never before possible. 
     Aspects of the loading and assembly of material with the drawing device  10  have been discussed and will be further discussed with regard to  FIGS.  7 - 12   . As noted above, the types of material, including the color, shape, and properties thereof can be varied according to the desires of the user. It is envisioned that the device can use various types of material, such as sugar, gummy (e.g., gelatin), isomalt, chocolate, dough (e.g., pasta dough, bread dough, cookie dough, etc., which can be cooked during/by the extrusion process), wax, animal fats, tapioca, cheese, toffy, jams, preserves, corn puffs, ground meat, meat, potatoes, or other edible materials or clays, ceramics, or other curable crafting materials. Such materials may be used and loaded into one or more of the chambers  150  of the cartridge  60 . 
     Optionally, the user may perform methods in which different material types are loaded into the same cartridge  60 , thereby allowing the user to define or perform a sequential process in which a first material is extruded onto a substrate, and thereafter, additional materials (which may have different colors, properties, or other characteristics) may be overlaid onto the first extruded material, thereby providing a complex interplay of layers and material properties, as desired by the user. For example, the chambers  150  can be loaded with pellets  32  of sugar that each have different colors. The operation of the drawing device  10  can thereby produce a multitude of sequential colors for the user. 
     Referring now to  FIGS.  7 - 12   , other aspects and operation of the drawing device  10  will be discussed in greater detail. 
     In accordance with some embodiments, the handheld extrusion drawing device provides the user with a controllable flow of material through the drawing device toward the nozzle assembly, for extrusion out of the exit nozzle. As noted above, various efforts have been made in conventional devices that fail to provide the user with a meaningful degree of uninterrupted, low-maintenance operation of the drawing device. Instead, such devices require significant user interaction and manipulation in order to reload material or load different types of materials. Further such devices also require that the user pause for significant periods of time while the device resets or becomes ready for additional use. Such devices tend to provide only a single, low-volume operation that requires the user to wait during phases of the operation of the device instead of providing a substantial amount of material with different, desired properties, in a substantially continuous operation, as disclosed in accordance with some embodiments therein. Accordingly, these and other advantages are possible using features of the drawing device disclosed herein. 
     The drawing device can advantageously incorporate a reloading mechanism. The drawing device can also comprise a retraction mechanism. The retraction mechanism can be manually or automatically activated. In accordance with some embodiments, these mechanisms can be incorporated into a single drawing device or the omitted from the drawing device, as desired. 
       FIGS.  7 - 12    illustrate various components of an embodiment of the drawing device  10 . While this embodiment illustrates a drawing device in which a retraction mechanism is used in conjunction with a reloading mechanism, these mechanisms can be incorporated independently of each other, and be manually or automatically activated. As discussed further herein, although the retraction mechanism and the reloading mechanism can operate or function in a dependent manner in the drawing device  10 , these mechanisms can also function independently of each other. 
       FIGS.  7  and  8    illustrate, bottom, rear perspective views of the drawing device  10  without the housing  12  in order to illustrate aspects of the components of the drawing device  10 .  FIGS.  9 - 12    illustrate side views of the drawing device  10 , with  FIGS.  9  and  10    illustrating cross-sectional views taken along section lines  9 - 9  of  FIG.  3   . Further,  FIGS.  11  and  12    illustrate side views of the drawing device  10 , wherein the housing has been omitted in order to show details of the components of the drawing device  10 .  FIGS.  9  and  11    illustrate the drawing device  10  in a state wherein the advancement mechanism is positioned in a fully extended position  250 .  FIGS.  10  and  12    illustrate the advancement mechanism in a fully retracted position. Furthermore,  FIGS.  9  and  11    also illustrate the reloading mechanism in a disengaged position.  FIGS.  10  and  12    illustrate the reloading mechanism in an engaged, driving position. 
       FIGS.  7  and  8    illustrate various components of the drawing device  10 .  FIG.  7    illustrates that the drawing device  10  can comprise a fixing or mounting plate  200 . The fixing plate  200  can be configured so as to allow various components of the drawing device  10  to be mounted or coupled thereto, including fixed, sliding, or rotational couplings, as illustrated in discussed herein. The fixing plate  200  can extend at least partially along a length of the drawing device  10  and be disposed within at least a portion of the housing  12 .  FIG.  8    illustrates the components of the drawing device  10  while omitting the fixing plate  200  in order to more clearly depict features of the components of the drawing device  10 . 
     As illustrated in  FIGS.  7  and  8   , the drawing device  10  can comprise a driving mechanism, such as motor  210 , that is operatively connected to a gear assembly  212  for driving motion of the material within the drawing device  10 . However, as noted above, some embodiments do not use a motor, but instead use a manually inputted driving force, such as a type of spring (coil or leaf), user-applied force, or other driving mechanism. Referring to  FIGS.  7  and  8   , the motor  210  and the gear assembly  212  can be actuated in response to a signal generated by electrical components  220  of the drawing device  10 , using the actuator  14 . The electrical components  220  can comprise one or more circuits, motherboards, PCBs, wires, batteries, such as rechargeable batteries, lights, and other electronic features that can allow the user to control one or more functions of the drawing device  10 . 
     The retraction mechanism can operate in conjunction with or in response to the motor  210  and the gear assembly  212 . For example, in the embodiment illustrated in these figures, the gear assembly  212  can comprise a skip gear  230  that permits the motor  210  to drive motion of the skip gear  230  in a single direction until the skip gear  230  rotates a predetermined amount, whereat the motor  210  can pause, thereby allowing the skip gear  230  to maintain a retraction-permitting position. Thus, the skip gear  230  can define a driving rotational position in which the teeth of the skip gear  230  are engaged with a rack  232  of the advancement mechanism  214  and a disengaged position in which teeth of the skip gear  230  are no longer engaged with teeth of the rack  232 , thereby allowing the rack  232  two move relative to the skip gear  230 . In some embodiments, a perimeter of the skip gear  230  can have a toothed portion and a toothless portion or section  234  in which there is a gap between the teeth of the skip gear  230 . The gap can be sufficiently wide to permit the rack  232  to become disengaged from the skip gear  230 . 
     The retraction mechanism can allow the motor  210  to advance the rack  232  to the fully extended position  250 , as shown in  FIG.  9   . The rack  232  can be driven to the fully extended position  250  by rotation of the skip gear  230 . However, at approximately the moment illustrated in  FIG.  9   , wherein teeth of the skip gear  230  are rotated beyond the position shown in  FIG.  9    and in the direction  254  illustrated therein, the skip gear can  230  can thereafter disengage from the rack  232  when a toothless portion  234  of the skip gear  230  is rotated to a position adjacent to the teeth of the rack  232 . 
     The disengagement between the skip gear  230  and the rack  232  is illustrated in  FIG.  10   . As shown therein, the teeth of the rack  232  are out of contact with the teeth of the skip gear  230  due to the rotational position of the skip gear  230 , in which the toothless portion  234  of the skip gear  230  is rotated to be adjacent to the teeth of the rack  232 . 
     In accordance with some embodiments, a cycle of the skip gear from a leading tooth  260  to a final tooth  262  can have a total drive time of between about 5 seconds and about 25 seconds, between about 10 seconds and about 20 seconds, or about 15 seconds. 
     Thus, upon actuation of the actuators  14 , the motor can drive the skip gear forward in the direction  254  at a rate in which about three quarters of the circumference or perimeter of the skip gear  230  completes a rotation in a given cycle time. 
     Optionally, the advancement mechanism  214  can be configured to permit the skip gear  230  to stay at the disengaged position  270  for a dedicated period of time without rotational movement or the skip gear  230  can continue to rotate at a constant rate, thereby providing sufficient time for the rack  232  to move from the fully extended position,  250  to the fully retracted position  252 . 
     The electrical components  220  of the drawing device  10  can be programmed to allow the drawing device  10  to function in a manner that allows a complete cycle to occur in which the skip gear  230  drives the rack  232  to the fully extended position  250  and then disengages from the rack  232  for a specific period of time until the rack  232  reaches the fully retracted position  252 . 
     In some embodiments, a cycle can be performed as the skip gear  230  completes a full rotation from the disengaged position  270 , shown in  FIG.  10   . Thus, the user can actuate, push, or trigger the actuator  14 , thereby causing the skip gear  230  to begin rotating from the disengaged position  270  until the teeth of the skip gear  230  begin to contact the teeth of the rack  232  and drive motion of the rack completely to the fully extended position  250 , whereafter continued motion of the skip gear  230  beyond the position shown in  FIG.  9    will cause the toothless portion  234  of the skip gear to reach the disengaged position  270 , as shown in  FIG.  10   . Once in the disengaged position  270 , the rack  232  can be manually or automatically driven or pulled or otherwise moved back to the fully retracted position  252 . 
     Retraction of the rack  232 , whether accomplished manually or automatically via a motor or other driving mechanism, can be facilitated using a mechanical component, such as a spring, which can contract or expand to urge the rack  232  away from the fully extended position  250 . 
     An embodiment of such a mechanical component is illustrated in  FIGS.  9  and  10    as the spring  280 . As shown in  FIGS.  9  and  10   , as the rack  232  is driven towards the fully extended position  250 , the spring  280  can be pulled and extended away from a rest position such that when the rack  232  reaches the fully extended position  250 , the spring  280  has a high degree of potential energy that can be used once the skip gear  230  reaches the disengaged position  270  in order to pull the rack  232  toward the fully retracted position  252 . 
     Alternatively, the spring  280  can be compressed as the rack  232  is driven toward the fully extended position  250 , whereafter the spring can expand and drive the rack  232  back toward the fully retracted position  252 . Other various configurations can be developed that allow the rack  232  to be driven toward the fully extended position,  250  and pulled or pushed back to the fully retracted position  252 . In this manner, the retraction mechanism can allow the user to selectively activate the advancement mechanism, driving the rack  232  forward until the pushrod  236  has urged all of the material out of the active chamber  150 , as shown in  FIG.  9   . Thereafter, the rack  232  and the pushrod  236  can be moved to the fully retracted position  252 , in which the pushrod  236  has fully exited the active chamber  150 . 
     Referring still to  FIGS.  7  and  8   , in accordance with some embodiments, the drawing device  10  can also comprise a reloading mechanism. The reloading mechanism can be manually or automatically activated. The reloading mechanism can comprise one or more components that are configured to move or rotate material within the housing so that the material can be driven toward the exit nozzle of the drawing device  10 . 
     For example, the material can be positioned in the chambers of the cartridge assembly and rotated sequentially so that the pushrod  40  drives the material toward the nozzle assembly  20  to be extruded out of the exit nozzle  50 . The reloading mechanism can function to reload or reposition material within the drawing device  10  in response to a signal from the user, a mechanical force within the drawing device  10  in the course of operation of other components or mechanisms within the drawing device  10 , or in response to a mechanical force exerted by the user. 
     In the embodiment illustrated in  FIGS.  7  and  8   , the reloading mechanism can comprise a driving linkage  300 , an index rod  302 , and a reverse linkage  304 . The driving linkage  300 , the index rod  302  and the reverse linkage  304  can functionally cooperate to convert linear movement to a rotational movement imparted to the cartridge  60  of the cartridge assembly  30 . 
     For example, the reverse linkage  304  can comprise an elongate member that is pivotally coupled to the fixing plate  200  in a manner that permits opposing ends to contact a portion of the rack  232  and the index rod  302 . The reverse linkage  304  can pivot between alternating positions and impart a force to the indexing rod  302  that can thereafter be imparted to the driving linkage  300  in order to actuate the reloading mechanism and thereby convert linear motion to rotational motion at the cartridge  60 . 
     The actuation of the reverse linkage  304  will now be described with reference to a first position shown in  FIGS.  9  and  11    a second position shown in  FIGS.  10  and  12   . For example, in  FIGS.  9  and  11   , the reverse linkage  304  is shown in a first position in which the rack  232  is in the extended position, and therefore, the rack  232  is not in contact with or does not exert a rotational force on the reverse linkage  304 . Accordingly, although the reverse linkage  304  may be in contact with the index rod  302 , the reverse linkage  304  may not exert a driving force on the index rod  302 . Accordingly, a biasing mechanism, such as the spring noted above, retains the or maintains the indexing rod  302  and the driving linkage  300  in a disengaged position. 
     However, referring to  FIGS.  10  and  12   , when the rack  232  rebounds or moves to the retracted position  252 , a portion of the rack  232 , or a component coupled thereto, such as an abutting member  320 , can the translated into contact against a rack end portion or element  330  of the reverse linkage  304 , thereby causing the reverse linkage  304  to pivot about its pivot point  306 , thereby moving an index end portion or element  332  of the reverse linkage  304  into contact with the index rod  302 . As the index end portion  332  contacts the index rod  302 , an axial force can be imparted to the index rod  302  by the index end portion  332  of the reverse linkage  304 , thereby driving translation or other movement of the index rod  302  and actuating the driving linkage  300 . 
     As the driving linkage  300  is actuated from a non-cartridge-driving position (shown in  FIGS.  9  and  11   ), the driving linkage  300  can contact an engagement member  340 , such as a protrusion or detent feature, of the cartridge  60  to drive motion of the cartridge  60  to a cartridge-driven position (shown in  FIGS.  10  and  12   ). Contact against the engagement member  340  via the driving linkage  300  can cause a rotational force to be exerted on the cartridge  60  about the cartridge axis  78 . 
     For example, referring to  FIG.  4   , the engagement member  340  of the cartridge  60  can extend in a radial direction from the cartridge axis  78  or center of the cartridge  60  along a proximal end of the cartridge  60 . The driving linkage  300  can comprise a driving member  342  that can rotate about a driving pivot point  344  (shown in  FIGS.  7 - 12   ) as the driving linkage  300  is contacted by a distal end portion or contact interface  346  of the index rod  302 . 
     As illustrated in  FIGS.  9  and  10   , the contact interface  346  of the index rod  302  can be shaped or configured to mate with the driving linkage  300  at different longitudinal positions in which the contact interface  346  portion abuts a portion of the driving linkage  300  (such as an intermediate or pivot linkage  348  that is pivotally coupled to the driving member  342 ). 
     Referring to  FIG.  9   , the contact interface  346  can comprise a first face disposed at a first angle, relative to the longitudinal axis  78  of the device  10 , which can contact the pivot link  348  when in the non-cartridge-driving position, shown in  FIGS.  9  and  11   . For example, the contact interface  346  can contact a side or face of the pivot link at a first pitch or angle that allows the contact interface  346  to generally match or mate against side or face of the pivot link  348  in the non-cartridge-driving position. 
     Further, the contact interface  346  can comprise a second face disposed at a second angle, relative to the longitudinal axis  78  of the device  10 , which can contact the pivot link  348  when in the cartridge-driven position, shown in  FIGS.  10  and  12   . For example, the contact interface  346  can contact the side or face of the pivot link  348  at a second pitch or angle that allows the contact interface  346  to generally match or mate against side or face of the pivot link  348  as the pivot link  348  moves toward the cartridge-driven position. 
     Further, as the index rod  302  is driven distally toward the cartridge-driven position, the cartridge  60  will rotate to axially align the next chamber with the push rod  40 . The movement of the driving linkage  300  to the cartridge-driven position creates contact against and rotation of the cartridge  60  from a prior or first rotational position to a second rotational position. In particular, as the driving linkage  300  is engaged and moves in response to the distal motion of the index rod  302  and the contact interface  346 , the pivot link  348  will pivot about the pivot point  344 . As this happens, the pivot link  348  can come into contact with a second sloped surface of the contact interface  346  of the index rod  302 , as shown in  FIG.  10   . 
     As noted above, the rack  232  can move between an extended position  250  and a retracted position  252 . In accordance with some embodiments, the rack  232  can engage with one or more biasing members along a proximal or distal end thereof. A biasing member can be directly or indirectly coupled to, mounted to, or in engagement with, an internal structure of the housing and directly or indirectly with a portion of the rack  232 , such that the biasing member is compressed or stretched as the rack  232  moves toward or is driven toward the extended position by action of the motor  210 . Once the rack  232  has reached the fully extended position  250 , the biasing member can drive the rack back to the disengaged position. 
     In some embodiments, once the rack  232  has reached the fully extended position  250 , the advancing mechanism  214  can use a skip gear  230  having a toothless portion  234 , as discussed above. Accordingly, during a disengaged state with the skip gear  230 , the rack  232  can be pushed or pulled back to the retracted position  252  by action of the rack biasing member. 
     Alternatively, once the rack  232  has reached the fully extended position  250 , the motor  210  can pause or enter an “off” state during which the biasing member drive or return the rack  232  to the retracted position  252  by overcoming a frictional force or idle state of the motor  210 , thereby cause a shaft of the motor  210  to spin in reverse in a reversing stage. The biasing member can thus drive the rack  232  back to the disengaged or retracted position  252  against friction of an inactive motor. In such embodiments, the motor can be in a powered off state or a non-driven state and simply be overcome by the biasing member. Accordingly, the motor can remain enmeshed or in rotational engagement with the rack  232  in such embodiments, and only exert a positive driving force on the rack  232  when actuated by the user, and only up to the fully extended position  250 . Thereafter, the motor  210  can be rotated backwards by function of the rack biasing member. 
     As noted above, the loading mechanism for the device can be configured can advantageously facilitate use of the 3D drawing pen, for example, by providing a substantial or semi-continuous supply of material to the nozzle assembly for extrusion and artistic creation. Various types of loading mechanisms, for example, including an advancement mechanism, a cartridge, a belt system, a hopper, a revolver cartridge, a screw drive system, a wave generator, and/or a reloader mechanism, can be incorporated into one or more embodiments of the 3D drawing pen.  FIGS.  13 A- 18    illustrate these and other features, which can be individually modified or interchangeably incorporated into one or more embodiments of the drawing pen disclosed herein. 
     Referring now to  FIGS.  13 A- 18   , the side views of embodiments of advancement and reloading mechanisms and components thereof that can optionally be incorporated into the drawing device, according to some embodiments. 
       FIGS.  13 A and  13 B  are side cross-sectional views of embodiments of a drawing device  400  having a loading mechanism  402  that comprises a revolver cartridge  404 . The revolver cartridge  404  can be coupled to the body of the drawing device  400  and rotatable about an axis  406 . The axis  406  can extend parallel relative to a longitudinal axis of an advancing mechanism or plunger  408 . As the cartridge  404  rotates about the axis  406 , individual slots or barrels  410  can be positioned to permit a pellet  412  of material to be loaded into the barrel  410 , rotated about the axis  406 , and driven from a ready or active position  420 . 
       FIGS.  13 A and  13 B  illustrate that the plunger  408  has moved all of the way into the barrel  414  so as to drive a pellet  412  of material into the heating element and out through the exit nozzle. One of the benefits of the embodiments shown in  FIGS.  13 A and  13 B  is that the revolver cartridge  404  is position such that the barrel  410  is exposed and available for loading. 
     As shown in  FIG.  13 A , the barrel  410  can be loaded in a direction toward the proximal end of the pen. However, some embodiments can be configured such that the barrel allows insertion of material in a direction toward the distal end or tip of the pen, as shown in  FIG.  13 B . 
       FIG.  14    illustrates an embodiment of a drawing device  450  having a loading mechanism  452  that comprises advancement and reloading mechanisms that use a clip or clip mechanism  454 . The clip  454  can carry several pellets  456  of material. In such embodiments, the clip  454  can be coupled to the device, such as along a side thereof, thereby enabling the material  456  housed within the clip to be delivered into the device for use. 
     For example, the clip  454  can comprise an inner volume into which the material  456  is loaded and a driving component that urges the material  456  out of the volume and into the device. The driving component can comprise a spring or other structure that provides a driving force to cause the material  456  to move toward a loading chamber  458  of the device. 
     Once positioned in the loading chamber  458  in a driving position, a pushrod  460  of the device can urge the material  456  toward the nozzle assembly for extrusion. The user can actuate the device (e.g., using a conventional actuation mechanism, such as via a button or other actuator, which can directly or indirectly permit the pushrod  460  to be in an activated state and axially driven by the spring force). 
     As in any of the embodiments shown in  FIGS.  1 - 18   , in some embodiments of the device  500 , the pushrod  460  can be manually activated, such as by allowing the user to pull the pushrod  460  against a spring force to preload the pushrod  460  to a driving position (pulled to arm the pushrod  460 ). 
     As in any of the embodiments shown in  FIGS.  1 - 18   , in some embodiments of the device  500 , the pushrod  460  can be activated by a motor, a type of spring (coil or leaf), user-applied force, or other driving mechanism, for example, that uses one or more gears to convert rotational force into linear motion of the pushrod  460 . 
     Upon actuation, the pushrod  460  can exert an axial force against the material  456  in the loading chamber  458 , thereby driving the material  456  toward the nozzle assembly and moving the pushrod  460  toward a driven position. The pushrod  460  can then be pulled back against the spring force toward the driving position, thereby clearing the loading chamber  458  and permitting the clip mechanism to urge additional material  456  into the loading chamber  458  so that the device is again in a ready state to permit the user to actuate the device and continue the extrusion process. 
       FIG.  15    illustrates an embodiment of a drawing device  500  having a loading mechanism  502  that comprises advancement and reloading mechanisms that use a belt drive mechanism  504 . The belt drive mechanism  504  can use a belt  504  that carries material  506  and can be fed into and through the device to rapidly load additional material  506  into a loading chamber  508  of the device. Once material  506  is positioned in the loading chamber  508 , the material  506  can be driven toward the nozzle assembly for extrusion by a pushrod  510 . 
     In some embodiments, the belt  504  can be drawn or mechanically pulled through the device, whether manually or automatically. The belt  504  can advance or be advanced each time material  506  carried by the belt  504  and positioned in the loading chamber  508  (e.g., axially aligned with the nozzle assembly). The advancement can thereby move additional material  506  carried by the belt  504  into a ready position for being driven by the pushrod  510 . As such, the user can complete subsequent cycles of in which material  506  is driven through the loading chamber  508  to the nozzle assembly. 
     The belt  504  can be fed into the housing of the device  500  through a first side aperture and out of a second side aperture as the belt  504  is advanced and used. The first and second side apertures can be disposed adjacent to a distal end portion of the housing of the device  500 , near the nozzle assembly. 
     In some embodiments, the belt  504  can be reusable, permitting the user to reload the belt  504  with additional material. Additionally, the belt  504  can be a single-use or disposable part. 
     For example,  FIG.  16    illustrates an embodiment of a drawing device  550  having a loading mechanism  552  that comprises a reloading mechanism that uses a screw drive mechanism  554 . Such embodiments can comprise an Archimedes screw  554  that can rotate within the device (e.g., within and driving material  556  toward a loading chamber  558 ) and permit material  556  to be driven within the device toward the nozzle assembly for extrusion. The material  556  can comprise pellets, such as spherical beads. 
     The screw  554  can be coupled to and driven via a motor, a type of spring (coil or leaf), user-applied force, or other driving mechanism. Whether motor or manually activated, the screw  554  can rotate upon actuation by the user to selectively feed material  556  toward the nozzle assembly. 
     Further, the material  556  can be fed into the loading chamber via a hopper that can be coupled to the device at a proximal end portion or side door or port of the device. 
     Next,  FIGS.  17 A and  17 B  illustrate an embodiment of a drawing device  600  having a loading mechanism  602  that comprises advancement and reloading mechanisms that use a push drive mechanism and hopper  604 . The push drive mechanism and hopper  604  can be manually or automatically activated. In some embodiments, the reloading mechanism can comprise a driving mechanism input that can activate the push drive mechanism and assist in evacuating and driving material  606  from the hopper  604  to the nozzle assembly. 
     Some embodiments can comprise a pushrod  610  that can reciprocate within the device  600  (e.g., within a loading chamber  608 ) and permit material  606  or consumables to be driven within the device  600  toward the nozzle assembly for extrusion. 
     The material  606  can comprise pellets, which can be of any geometry, such as a non-uniform or variable geometry. Further, the material  606  can be fed into the loading chamber  608  via the hopper  604 . 
     In some embodiments, the hopper  604  can be removably coupled to the device  600  at a proximal end portion or side door or port of the device  600 . The push rod mechanism  610  can compact and drive the material  606  with power input (e.g., DC or stored energy or manual input, and drive the pushrod  610  from an open or loading position as shown in  FIG.  17 A  to a compacting or driven position, as shown in  FIG.  17 B ) 
     Finally,  FIG.  18    illustrates yet another embodiment of a drawing device  650  having a loading mechanism  652  that comprises advancement and reloading mechanisms. In  FIG.  18   , the reloading mechanism using a wave generator mechanism  652 . In such embodiments, material  656  can be loaded into the device  650  into a rear entry aperture (not shown) at a proximal end of the device and/or via a hopper or other material-carrying cartridge. For example, the aperture can comprise a restrictor that permits insertion of material into the aperture, but restricts accidental removal (e.g., by gravity) of the material  656  therefrom. 
     Once in the device  650 , the material  656  can be driven within the device  650  toward the nozzle assembly for extrusion using the wave generator mechanism  652 . The wave generator mechanism  652  can comprise an actuator portion  660  that produces and transmits a linear actuation to the material or pellets  656 , such as by ultrasonically driven or undulation mechanics. Optionally and/or alternatively, the actuator portion  660  can also generate a compressive, rolling action or peristaltic action that urges material  656  through the device  650  toward the nozzle assembly. 
     Advantageously, the hoppers, cartridges, clips, and belts that can be used in accordance with some embodiments of the reloading mechanisms provide a quick and simple manner of achieving steady or continuous usage of the device, with minimal interruption to the user. These and other features can allow the user to focus more on the actual work being performed using the device rather than getting the device to work properly. 
     Illustration of Subject Technology as Clauses 
     Various examples of aspects of the disclosure are described as numbered clauses (1, 2, 3, etc.) for convenience. These are provided as examples, and do not limit the subject technology. Identifications of the figures and reference numbers are provided below merely as examples and for illustrative purposes, and the clauses are not limited by those identifications. 
     Clause 1. A handheld drawing device comprising: a housing having an internal volume, a longitudinal axis, and a port that permits access to the internal volume of the housing a nozzle assembly coupled to the housing and comprising an exit nozzle and a heating element for melting a pellet of material; and a loading mechanism being configured to permit the pellet to be driven to and supported at an active position within the housing to permit the heating element to melt the pellet. 
     Clause 2. The drawing device of Clause 1, wherein the loading mechanism is configured to support the pellet at the port of the housing. 
     Clause 3. The drawing device of any of the preceding Clauses, wherein the loading mechanism comprises a cartridge that is removably couplable to the port of the housing. 
     Clause 4. The drawing device of Clause 3, wherein the cartridge having a rotation axis and a plurality of chambers disposed thereabout, each of the plurality of chambers being configured to support a plurality of pellets therein and being rotatable about the rotation axis to selectively position an active chamber of the plurality of chambers in alignment with the longitudinal axis at an active position. 
     Clause 5. The drawing device of Clause 4, wherein the loading mechanism further comprises an advancing mechanism for causing rotation of the cartridge and driving the pellet from the active chamber toward the heating element. 
     Clause 6. The drawing device of Clause 5, further comprising a pushrod disposed within the housing and translatable along the longitudinal axis, the pushrod being movable into the active chamber toward an extended position for driving the pellet out of the active chamber toward the heating element for melting the pellet and extruding the material. 
     Clause 7. The drawing device of Clause 6, wherein the advancing mechanism comprises a link system that is actuated by movement of the pushrod in a direction away from the extended position to cause the link system to contact a driving member against a cartridge for positioning additional material to the active position. 
     Clause 8. The drawing device of Clause 7, wherein the link system comprises a pivoting reverse linkage, a driving rod, and a pivoting advancement linkage. 
     Clause 9. The drawing device of Clause 6, further comprising a motor configured to drive motion of the pushrod to the extended position. 
     Clause 10. The drawing device of Clause 9, wherein the pushrod is coupled to a rack that engages with a gear of the motor. 
     Clause 11. The drawing device of Clause 6, further comprising a spring mechanism configured to drive motion of the pushrod to the extended position. 
     Clause 12. The drawing device of Clause 6, wherein the pushrod automatically returns to a loading position from the extended position. 
     Clause 13. The drawing device of Clause 6, further comprising an actuator configured to activate a motor to control movement of the pushrod and thereby extrude the pellet from the exit nozzle. 
     Clause 14. The drawing device of Clause 6, further comprising a reversing mechanism configured to drive the pushrod out of a loading chamber of the device. 
     Clause 15. The drawing device of Clause 14, wherein the reversing mechanism comprises a spring configured to urge the pushrod away from the active chamber. 
     Clause 16. The drawing device of Clause 14, wherein the pushrod comprises a rack that is matingly engaged with a gear drive. 
     Clause 17. The drawing device of Clause 4, wherein each of the plurality of chambers is cylindrical. 
     Clause 18. The drawing device of Clause 3, wherein the cartridge comprises five chambers. 
     Clause 19. The drawing device of Clause 3, wherein the cartridge comprises at least two chambers. 
     Clause 20. The drawing device of Clause 3, wherein the cartridge is coupled to a removable cover portion of the housing, the cartridge and the removable cover portion cooperating as a single unit to permit insertion or removal of the cartridge from the housing. 
     Clause 21. The drawing device of Clause 20, wherein the removable cover portion comprises an external surface that matches a contour or surface continuity of an exterior surface of the housing adjacent to the port. 
     Clause 22. The drawing device of any of the preceding Clauses, wherein the loading mechanism comprises a clip mechanism. 
     Clause 23. The drawing device of any of the preceding Clauses, wherein the loading mechanism comprises a revolver cartridge. 
     Clause 24. The drawing device of any of the preceding Clauses, wherein the loading mechanism comprises a belt wherealong a plurality of pellets of material are supported. 
     Clause 25. The drawing device of any of the preceding Clauses, wherein the loading mechanism comprises a screw drive mechanism. 
     Clause 26. The drawing device of any of the preceding Clauses, wherein the loading mechanism comprises a manual pushrod mechanism. 
     Clause 27. The drawing device of any of the preceding Clauses, wherein the loading mechanism comprises a wave generator mechanism. 
     Clause 28. The drawing device of any of the preceding Clauses, wherein the exit nozzle is positioned along the longitudinal axis. 
     Clause 29. The drawing device of any of the preceding Clauses, wherein the heating element is positioned intermediate the exit nozzle and the loading mechanism. 
     Clause 30. The drawing device of any of the preceding Clauses, wherein the housing being configured to fit in a user&#39;s hand and configured without a handle substantially perpendicular to the housing. 
     Clause 31. The drawing device of any of the preceding Clauses, wherein the drawing device is a three-dimensional (3D) drawing pen that is configured to permit drawing in 3D space. 
     Clause 32. The drawing device of any of the preceding Clauses, wherein the heating element is positioned adjacent to the exit nozzle and configured to melt the pellet of material prior to extrusion through the exit nozzle. 
     Clause 33. The drawing device of any of the preceding Clauses, wherein the housing comprises a length between a first end and a second end, the length being greater than a maximum transverse extent of the housing. 
     Clause 34. The drawing device of any of the preceding Clauses, wherein the device is configured to extrude the pellet out of the exit nozzle in a continuous, vertical form. 
     Clause 35. A handheld drawing device comprising: a housing having an internal volume, a longitudinal axis, and a port that permits access to the internal volume of the housing; a loading mechanism that is removably couplable to the port of the housing, the loading mechanism being configured to support consumable material therein and being configured to selectively position the material in alignment with the longitudinal axis at an active position; and a nozzle assembly coupled to the housing and comprising an exit nozzle and a heating element. 
     Clause 36. The drawing device of Clause 35, wherein the loading mechanism comprises a cartridge that is removably insertable into the port of the housing, the cartridge having a rotation axis and a plurality of chambers disposed thereabout, each of the plurality of chambers being configured to support a pellet of material therein and being rotatable about the rotation axis to selectively position an active chamber of the plurality of chambers in alignment with the longitudinal axis at an active position. 
     Clause 37. The drawing device of Clause 36, further comprising a pushrod disposed within the housing and translatable along the longitudinal axis, the pushrod being movable into the active chamber toward an extended position for driving the pellet out of the active chamber toward the heating element for melting the pellet and extruding the material. 
     Clause 38. The drawing device of Clause 37, further comprising a motor configured to drive motion of the pushrod to the extended position. 
     Clause 39. The drawing device of Clause 38, wherein the pushrod is coupled to a rack that engages with a gear of the motor. 
     Clause 40. The drawing device of Clause 37, further comprising a spring mechanism configured to drive motion of the pushrod to the extended position. 
     Clause 41. The drawing device of Clause 38, further comprising an actuator configured to activate the motor to control movement of the pushrod and thereby extrude the pellet from the exit nozzle. 
     Clause 42. The drawing device of Clause 37, further comprising an advancing mechanism for causing rotation of the cartridge. 
     Clause 43. The drawing device of Clause 42, wherein the advancing mechanism comprises a link system that is actuated by movement of the pushrod in a direction away from the extended position. 
     Clause 44. The drawing device of Clause 43, wherein the link system comprises a pivoting reverse linkage, a driving rod, and a pivoting advancement linkage. 
     Clause 45. The drawing device of any of Clauses 35-44, wherein the exit nozzle is positioned along the longitudinal axis. 
     Clause 46. The drawing device of Clause 36, wherein the cartridge comprises five chambers. 
     Clause 47. The drawing device of Clause 36, wherein the cartridge comprises at least two chambers. 
     Clause 48. The drawing device of Clause 36, wherein the heating element is positioned intermediate the exit nozzle and the loading mechanism. 
     Clause 49. The drawing device of Clause 36, wherein each of the plurality of chambers is cylindrical. 
     Clause 50. The drawing device of Clause 37, wherein the pushrod automatically returns to a loading position from the extended position. 
     Clause 51. The drawing device of Clause 37, further comprising a reversing mechanism configured to drive the pushrod out of a loading chamber of the device. 
     Clause 52. The drawing device of Clause 51, wherein the reversing mechanism comprises a spring configured to urge the pushrod away from the active chamber. 
     Clause 53. The drawing device of Clause 51, wherein the pushrod comprises a rack that is matingly engaged with a gear drive. 
     Clause 54. The drawing device of Clause 36, wherein the cartridge is coupled to a cover portion of the housing, the cartridge and the cover portion cooperating as a single unit to permit insertion or removal of the cartridge from the housing and to provide surface continuity for an exterior of the housing adjacent to the port. 
     Clause 55. The drawing device of any of Clauses 35-54, wherein the housing is configured to fit in a user&#39;s hand as a pen and configured without a handle substantially perpendicular to the housing. 
     Clause 56. The drawing device of any of Clauses 35-55, wherein the drawing device is a three-dimensional (3D) drawing pen that is configured to permit drawing in 3D space. 
     Clause 57. The drawing device of any of Clauses 35-56, wherein the housing comprises an upper housing and a lower housing, at least one of the upper housing and the lower housing comprising a cooling port proximate to the nozzle assembly. 
     Clause 58. The drawing device of any of Clauses 35-57, wherein the heating element is positioned adjacent to the exit nozzle and configured to melt the material prior to extrusion through the exit nozzle. 
     Clause 59. The drawing device of any of Clauses 35-58, wherein the housing comprises a length between a first end and a second end, the length being greater than a maximum transverse extent of the housing. 
     Clause 60. The drawing device of any of Clauses 35-59, wherein the device is configured to extrude a pellet of material out of the exit nozzle in a continuous, vertical form. 
     Clause 61. A modular cartridge assembly for use in a handheld drawing device, the assembly comprising a mounting component having an engagement cavity, a cartridge having a plurality of chambers and being configured to be received at least partially within the engagement cavity, and a cover member having an engagement section to which engagement members of the mounting component can be coupled for mounting the cartridge against the cover member to permit the cartridge to rotate about a longitudinal axis to align an active chamber of the plurality of chambers in a target position relative to the cover member. 
     Clause 62. The cartridge assembly of Clause 61, further comprising a mounting bracket extending from the cover member, the mounting bracket defining a cartridge receptacle into which the cartridge is received in an assembled configuration in which the mounting component is coupled to the cover member. 
     Clause 63. The cartridge assembly of Clause 62, wherein the mounting bracket comprises a discharge aperture with which the active chamber can be rotationally aligned. 
     Clause 64. The cartridge assembly of Clause 61, further comprising a plurality of magnetic coupling members. 
     Clause 65. A drawing device comprising the cartridge assembly of any of Clauses 61-64. 
     Clause 66. A handheld drawing device comprising: a housing having an internal volume, a longitudinal axis, and a port that permits access to the internal volume of the housing; a cartridge that is removably insertable into the port of the housing, the cartridge having a rotation axis and a plurality of chambers disposed thereabout, each of the plurality of chambers being configured to support a pellet of material therein and being rotatable about the rotation axis to selectively position an active chamber of the plurality of chambers in alignment with the longitudinal axis at an active position; and an advancing mechanism configured to drive material out of the active chamber when positioned at the active position, the advancing mechanism comprising a pushrod having an extended position and a retracted position, the pushrod being movable to the extended position to drive the material out of the active chamber and being configured to move to the retracted position. 
     Clause 67. The drawing device of Clause 66, wherein the advancing mechanism comprises a motor and a skip gear coupled to the motor for driving the pushrod to the extended position, the motor being configured to rotate the skip gear to a position in which the pushrod is disengaged with the skip gear for permitting the pushrod to be moved to the retracted position. 
     Clause 68. The drawing device of Clause 67, wherein the pushrod is coupled to a spring that exerts a retracting force on the pushrod for automatically retracting the pushrod when the pushrod is disengaged from the skip gear. 
     Clause 69. The drawing device of any of Clauses 66-68, wherein the pushrod is coupled to a spring that exerts a retracting force on the pushrod for automatically retracting the pushrod from the extended position toward the retracted position. 
     Clause 70. A handheld drawing device comprising: a housing having an internal volume, a longitudinal axis, and a port that permits access to the internal volume of the housing; a cartridge that is removably insertable into the port of the housing, the cartridge having a rotation axis and a plurality of chambers disposed thereabout, each of the plurality of chambers being configured to support a pellet of material therein and being rotatable about the rotation axis to selectively position an active chamber of the plurality of chambers in alignment with the longitudinal axis at an active position; and a rotating mechanism configured to rotate the cartridge to align another of the plurality of chambers at the active position. 
     Clause 71. The drawing device of Clause 70, wherein the rotating mechanism comprises a driving linkage configured to convert longitudinal motion to drive a rotational motion of the cartridge. 
     Clause 72. The drawing device of Clause 71, further comprising an advancing mechanism that is configured to drive material from the active chamber for extruding from the drawing device and, upon return to a retracted position, provide a longitudinal force that activates the driving linkage. 
     Clause 73. The drawing device of any of the preceding Clauses, further comprising a loading mechanism and an advancement mechanism that drives material from an active chamber of the device toward the nozzle assembly. 
     Clause 74. The drawing device of any of the preceding Clauses, further comprising a loading mechanism that comprises a clip mechanism, a screw drive mechanism, a belt mechanism, a manual pushrod mechanism, and/or a wave generator mechanism. 
     Further Considerations 
     In some embodiments, any of the clauses herein may depend from any one of the independent clauses or any one of the dependent clauses. In one aspect, any of the clauses (e.g., dependent or independent clauses) may be combined with any other one or more clauses (e.g., dependent or independent clauses). In one aspect, a claim may include some or all of the words (e.g., steps, operations, means or components) recited in a clause, a sentence, a phrase or a paragraph. In one aspect, a claim may include some or all of the words recited in one or more clauses, sentences, phrases or paragraphs. In one aspect, some of the words in each of the clauses, sentences, phrases or paragraphs may be removed. In one aspect, additional words or elements may be added to a clause, a sentence, a phrase or a paragraph. In one aspect, the subject technology may be implemented without utilizing some of the components, elements, functions or operations described herein. In one aspect, the subject technology may be implemented utilizing additional components, elements, functions or operations. 
     The foregoing description is provided to enable a person skilled in the art to practice the various configurations described herein. While the subject technology has been particularly described with reference to the various figures and configurations, it should be understood that these are for illustration purposes only and should not be taken as limiting the scope of the subject technology. 
     There may be many other ways to implement the subject technology. Various functions and elements described herein may be partitioned differently from those shown without departing from the scope of the subject technology. Various modifications to these configurations will be readily apparent to those skilled in the art, and generic principles defined herein may be applied to other configurations. Thus, many changes and modifications maybe made to the subject technology, by one having ordinary skill in the art, without departing from the scope of the subject technology. 
     It is understood that the specific order or hierarchy of steps in the processes disclosed is an illustration of exemplary approaches. Based upon design preferences, it is understood that the specific order or hierarchy of steps in the processes may be rearranged. Some of the steps maybe performed simultaneously. The accompanying method claims present elements of the various steps in a sample order, and are not meant to be limited to the specific order or hierarchy presented. 
     As used herein, the phrase “at least one of” preceding a series of items, with the term “and” or “or” to separate any of the items, modifies the list as a whole, rather than each member of the list (i.e., each item). The phrase “at least one of” does not require selection of at least one of each item listed; rather, the phrase allows a meaning that includes at least one of any one of the items, and/or at least one of any combination of the items, and/or at least one of each of the items. By way of example, the phrases “at least one of A, B, and C” or “at least one of A, B, or C” each refer to only A, only B, or only C; any combination of A, B, and C; and/or at least one of each of A, B, and C. 
     Terms such as “top,” “bottom,” “front,” “rear” and the like as used in this disclosure should be understood as referring to an arbitrary frame of reference, rather than to the ordinary gravitational frame of reference. Thus, a top surface, a bottom surface, a front surface, and a rear surface may extend upwardly, downwardly, diagonally, or horizontally in a gravitational frame of reference. 
     Furthermore, to the extent that the term “include,” “have,” or the like is used in the description or the claims, such term is intended to be inclusive in a manner similar to the term “comprise” as “comprise” is interpreted when employed as a transitional word in a claim. 
     As used herein, the term “about” is relative to the actual value stated, as will be appreciated by those of skill in the art, and allows for approximations, inaccuracies and limits of measurement under the relevant circumstances. In one or more aspects, the terms “about,” “substantially,” and “approximately” may provide an industry-accepted tolerance for their corresponding terms and/or relativity between items, such as a tolerance of from less than one percent to ten percent of the actual value stated, and other suitable tolerances. 
     As used herein, the term “comprising” indicates the presence of the specified integer(s), but allows for the possibility of other integers, unspecified. This term does not imply any particular proportion of the specified integers. Variations of the word “comprising,” such as “comprise” and “comprises,” have correspondingly similar meanings. 
     The word “exemplary” is used herein to mean “serving as an example, instance, or illustration.” Any embodiment described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments. 
     A reference to an element in the singular is not intended to mean “one and only one” unless specifically stated, but rather “one or more.” Pronouns in the masculine (e.g., his) include the feminine and neuter gender (e.g., her and its) and vice versa. The term “some” refers to one or more. Underlined and/or italicized headings and subheadings are used for convenience only, do not limit the subject technology, and are not referred to in connection with the interpretation of the description of the subject technology. All structural and functional equivalents to the elements of the various configurations described throughout this disclosure that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and intended to be encompassed by the subject technology. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the above description. 
     Although the detailed description contains many specifics, these should not be construed as limiting the scope of the subject technology but merely as illustrating different examples and aspects of the subject technology. It should be appreciated that the scope of the subject technology includes other embodiments not discussed in detail above. Various other modifications, changes and variations may be made in the arrangement, operation and details of the method and apparatus of the subject technology disclosed herein without departing from the scope of the present disclosure. In addition, it is not necessary for a device or method to address every problem that is solvable (or possess every advantage that is achievable) by different embodiments of the disclosure in order to be encompassed within the scope of the disclosure. The use herein of “can” and derivatives thereof shall be understood in the sense of “possibly” or “optionally” as opposed to an affirmative capability.