The gearbox has a 10:1 ratio, which is part of a bigger project I'm working on. 12 VDC Motor, 60 RPM, High Torque http://www.amazon.com/exec/obidos/ASIN/B00BX54O8A/donscollecti Bearings, perfect size for 5mm bolt to go through. http://www.amazon.com/exec/obidos/ASIN/B00F4M1B7A/donscollecti 8-20-15: Added STL of complete assembly to assist in seeing how the gears are positioned. There are a couple possibly combinations. For the LEGO mounting kit, see thing: http://www.thingiverse.com/thing:992083 The noise in the background is my printer running, it never stops! http://youtu.be/ZrPO8_jl2lg http://youtu.be/u9x0sFstHQEPLA 20%, .2 layer, 2 shells The M5 nuts, .1 layer, 3 bottom layers, 4 top layers, and 4 shells. I also printed the M5 bolts for early prototype, The design takes two of the reduction gear set and tthree 10mm sleeves. Home Depot Partno, Description, Qty Needed 561-492, CAP SCREW 5mm-.8x40mm , 2 pieces 561-590, CAP SCREW 5MM-.8x50mm, 1 pieces 594-766, HEX NUT M5-.8mm , 5 pieces or print 366-757, FLAT WASHERS M5, 4 pieces 12 VDC Motor http://www.amazon.com/exec/obidos/ASIN/B00BX54O8A/donscollecti I used a CAT6 connector to wire it up. The gear with the threads is off pitch by 15 degrees on purpose, it will thread onto M5 bolt fine, use a nut against the gear to secure it. I included the drive coupler I'm using, which may not meet your projects needs, just adapt the other end to whatever you want.