This is a quick to print, handy little thing to hold my hex shank drill bits. I use these in my screwdriver/electric screwdriver for post processing prints. It lets me see the numbers on the side of the bits too.

The bits are snug, but not held tightly. Scale it down 1-2% for a friction fit (tested).

This is the bit set in the picture, they're not amazingly sharp but good enough for plastic. http://www.ebay.co.uk/itm/370962314440?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649