Harmonic Drive

thingiverse

Print the rotor and the casing out of a hard plastic, and the spline cup out of a flexible one. IMPORTANT: this needs lubrication! I used a silicone oil, but mineral oil should work too. It doesn't take much. I haven't tried a dry lubricant like PTFE, but it might work. Whatever you do, don't use supports on the spline cup. Update: I accidentally uploaded the wrong SplineCup.stl. I've replaced it with the correct one.