I made this specifically for this motor: http://www.allelectronics.com/make-a-store/item/smt-107/stepper-motor-w/gear-train/1.html Since it's a cheap stepper motor with good quality (came from commercial/industrial equipment I assume) and I couldn't for the life of me pull off the brass gear that is press-fitted, I gave in and made a pulley that pushes over the gear. It's a bit of a tight fit, and it may be slightly different depending on your printer, I printed mine with a Makerbot Replicator 2.