The Finger Flexor Tendon Anatomy Model (Left Index) is an educational model created by Janson to demonstrate the action of finger FDP & FDS flexor tendons gliding through the A2 and A4 pulleys. Credit to Siderits "Human Hand Bones" (https://www.thingiverse.com/thing:15342) for 3D models of the finger bones (Janson added pulleys and holes for articulation). Requires additional materials and assembly to complete.
Print with rafts and supports. I prefer to print the bones vertical to avoid "scarring" from support material removal along the sides of the bones. Recommend 3 shells, 10% infill, 2mm layer height for metacarpal & proximal phalanx and 1 or 1.5mm layer height for middle and distal phalanges (due to smaller size). Be sure to smooth all rough surfaces during post-processing.
1. Use 1 or 1.5mm elastic cord (available in sewing stores) to articulate joints. Loop through holes in the adjacents bones 2 to 3 times. Be careful not to over tighten elastic cords. Joints should move freely. Once proper tension is set, tuck free ends of elastic cords into bone holes and glue (cyanoacrylate) cord ends in place.
2. For the Flexor Digitorum Profundus (FDP) tendon (shown in blue in the images) use a 1.5mm non-elastic cord. Tie a knot in one end and thread other end of cord through the hole in the distal phalanx, A4 and A2 pulleys as well as the palmar aponeurosis (PA).
3. For the Flexor Digitorum Superficialis (FDS) tendon use a .75mm nano paracord (non-elastic) (colored yellow in the images). Fold cord in half and thread ends through each holes in the middle phalanx. Bring the two cords together to make a "V" over the middle phalanx. Glue the remainder of the cord below the "V" together to make a single cord (see images). Once glue is set, thread the FDS cord through the A2 pulley and palmar aponeurosis (PA). *If you find a better method for creating a FDS tendon for this model - please message me.
Once assembled, pull on the ends of the FDP and FDS cords to actively flex the finger joints.