print list:

• crank_arm.stl
• crank_handle.stl
• primary_gear.stl
• secondary_gear.stl
• frame_front.stl
• frame_back.stl
• (optional) bushings.stl

you will also need 4x RS608 bearings, and some round tubing with 8mm outer diameter for the axels, two lengths, about 100mm each.

No support material required. All bearings and axels are press fits, with a through hole for a pin/screw to stop slippage on the primary gear and crank handle. The holes in the secondary gear accept RS6200 bearings to add some more inertia.

Designed for spinning up one of these wrist exercise tools: https://en.wikipedia.org/wiki/Gyroscopic_exercise_tool

Works a treat, but pretty noisy. Enjoy.