Ho semplicemente postato questa idea che ho trovato su questo sito http://www.p3-d.com/twist-drill.htmlnstructions and Usage: Works with #37 (.104" / 2.64mm) drill bits May accommodate slightly larger or smaller bits (use at your own risk) Download and print all 4 STL files (Helix, Nut, Hand Grip, Finger Rest) Suggest printing at fine layer height (.1mm) Suggest a highly calibrated printer Suggest using raft on the helix component During assembly, it helps to put a tiny drop of grease on the tip of the finger rest before pressing it into the helix. It should snap in snugly, but turn freely