v4.2 : This time inspired by jwest007 Taz Z motor coupler, replacing M3 nut hole by a simple hole for M3 heatset insert. I also added some support at M6 nut hole entry for good bridging at the edge. The Freecad model is not really "clean". I'll redo it from scratch later. v4.1 : Initaly this thing is a mod of Eric's improved Z axis coupler. I reduced a litle bit the M6 nut hole. 10mm wide and 1mm smaller for height. This to be closer to the one I intend to use. I enlarged one M3 hole in order to use a nylstop nut. I kept the bridge version for the moment, that's fine for the whole M6 hole yet it's not really good for the entry. I think I'll had just one or two support for entry. I also think about removing the opposite M3 nut hole. On my side I'm working with Freecad. I provided the one I worked on. And thank you again to Eric for this coupler.