In those mechanisms, a high-torque, low backlash gearbox might be just the thing, and a 3D printable split planetary harmonic ... we can see the benefits of the design, and it has some nice ...

[Retsetman]’s version has three circular elements nested together on a common axis, and while not exactly a planetary ... gearbox appears to be a refinement on [Retsetman]’s earlier design ...