A QUICK TEST get the optimum hole size for you're OPEN-SCAD designs, there are a series of holes, in increacing sizees, For M3 Clearence, M3 Nut, M3 Pan-head, And M3 Tap - the 7 side hole, which I hope will allow the tap to start a bit easier. Enjoy CeriI recomend you check the SCAD file, Because, this one printed out a bit TOO tight, I guess I should have set 0.2 steppes, not 0.1 steppes. ooopppss !!