Model originally uploaded to Thingiverse at https://www.thingiverse.com/thing:2789709.

I had a stepper motor from an old printer with a press-fit timing gear already in place, so I made this pulley to adapt an M8 Greg-Wade geared extruder derivative to belt drive. I know there are other designs which are already belt drive, but I was looking for something I could make with parts I had on hand, namely 608 skate bearings and the pre-fitted timing pulley. Plus I had already been running the geared version, so the pulley was the only new component to print. Though I did have to order in the timing belt, T2.5 - 6mm wide, 200mm long.