This is a guitar string winder. It makes changing strings a much quicker task.Just print it out, and it snaps together, no tools or screws required. The pin fits through the crank and into the handle. It's s friction fit of the pin into the handle, but the crank should turn freely, but be held captive by the pin.The canonical openscad file for this design is on github: http://github.com/smcameron/guitar_string_winder