SummaryI was obsessed with the size in 31mm and out 42mm of nema17 motor it's very small to make a gearbox, f****ing :P Compact Simply Suitable material Compatible with a variety of Bowden Efficiency… it's just an idea Using Pulley and Rubber band, Material: plastic or aluminium 1x pulley input 1x pulley output 4x plulley 2 stages 5 rubber band < 3mm (length, don't know :p) 1x bearing 625zz Ratio: 1.51:1 for one stage Totall: 10:1 with 5 stages, (nice :P) Dimensions: 44x44x26 Please give me your opinion! Fun!