A foot support system, comprising: a first sheet of thermoplastic material; and a second sheet of thermoplastic material sealed to the first sheet of thermoplastic material, wherein seal lines joining the first sheet of thermoplastic material to the second sheet of thermoplastic material are shaped to form: a first fluid-filled bladder chamber defining a first interior chamber between the first sheet of thermoplastic material and the second sheet of thermoplastic material; a second fluid-filled bladder chamber defining a second interior chamber between the first sheet of thermoplastic material and the second sheet of thermoplastic material; and a first fluid flow line (106, 206, 216, 124) placing the first interior chamber and the second interior chamber in fluid communication with one another, wherein the first fluid-filled bladder chamber is positioned with respect to the second fluid-filled bladder chamber so that in the foot support system: (a) a portion of an exterior surface (102M2) of the second sheet of thermoplastic material defining the first fluid-filled bladder chamber directly faces a portion of the exterior surface (104M2) of the second sheet of thermoplastic material defining the second fluid-filled bladder chamber and (b) a portion of an exterior surface (102M1) of the first sheet of thermoplastic material defining the first fluid-filled bladder chamber faces away from a portion of the exterior surface (104M1) of the first sheet of thermoplastic material defining the second fluid-filled bladder chamber. a first sheet of thermoplastic material; and a second sheet of thermoplastic material sealed to the first sheet of thermoplastic material, wherein seal lines joining the first sheet of thermoplastic material to the second sheet of thermoplastic material are shaped to form: a first fluid-filled bladder chamber defining a first interior chamber between the first sheet of thermoplastic material and the second sheet of thermoplastic material; a second fluid-filled bladder chamber defining a second interior chamber between the first sheet of thermoplastic material and the second sheet of thermoplastic material; and a first fluid flow line (106, 206, 216, 124) placing the first interior chamber and the second interior chamber in fluid communication with one another, a first fluid-filled bladder chamber defining a first interior chamber between the first sheet of thermoplastic material and the second sheet of thermoplastic material; a second fluid-filled bladder chamber defining a second interior chamber between the first sheet of thermoplastic material and the second sheet of thermoplastic material; and a first fluid flow line (106, 206, 216, 124) placing the first interior chamber and the second interior chamber in fluid communication with one another, wherein the first fluid-filled bladder chamber is positioned with respect to the second fluid-filled bladder chamber so that in the foot support system: (a) a portion of an exterior surface (102M2) of the second sheet of thermoplastic material defining the first fluid-filled bladder chamber directly faces a portion of the exterior surface (104M2) of the second sheet of thermoplastic material defining the second fluid-filled bladder chamber and (b) a portion of an exterior surface (102M1) of the first sheet of thermoplastic material defining the first fluid-filled bladder chamber faces away from a portion of the exterior surface (104M1) of the first sheet of thermoplastic material defining the second fluid-filled bladder chamber. (a) a portion of an exterior surface (102M2) of the second sheet of thermoplastic material defining the first fluid-filled bladder chamber directly faces a portion of the exterior surface (104M2) of the second sheet of thermoplastic material defining the second fluid-filled bladder chamber and (b) a portion of an exterior surface (102M1) of the first sheet of thermoplastic material defining the first fluid-filled bladder chamber faces away from a portion of the exterior surface (104M1) of the first sheet of thermoplastic material defining the second fluid-filled bladder chamber.