Print it with 6mm hole on flat.steps after print:- put 8mm rod in hole- attach other hole on drill bit - move down drill on flat.- lock rod with clamp...- move up plastic on drill bi- drill it.
need try it soon...curently center manualy (photo) but i need make it more simple.
soon try it for now add (in test in title) i update it and my g+ when try it.