Parts Required: Printed Parts (I have plated the STL's for easy printing) Qty:2 - 608 Skate Bearings (low friction bearing like whatwere used in old fidget spinners work best) Qty:21 - 3/8" Hex nuts to act as flywheel mass (let me know if you want one for metric hardware as the weights) Qty:1 - 3mm x 45mm long bolt Qty:1 - 3mm hex nylock nut Optional: A few 3mm washers to space out the sides if center rubs