Made a recumbent idler pulley out of an old Skateboard wheel, using a high RPM rotary tool, a vice, a skateboard truck, and a "beaver tail" file. i also used calipers to help match the size and shape of the original idler pulleys that came on my recumbent. The rotary bit pressing onto skateboard wheel to make it spin was made from a die-grinder sander bit with rubber pad removed but you could use another home-made bit as long as its smooth and round. Wear eye protection! Wear thick leather gloves and a good respirator!
Heres a video of me carving away at skateboard wheel:
Heres some of the tools i used:
