Great design. The bit holders were too tight, they didn't come close to being big enough to hold any of my mini bits from any manufacturer. This was with PLA, so I'm sure there was a little bit of shrinkage but not a lot. I ended up printing it in ABS where I changed the x & y axis to be 107.5% and that worked pretty well. It could be probably 104 and still fit tight, they're a bit lose at 107.5 (plus ABS does shrink more than PLA I believe). The white version is the PLA in the image where you can see both, to show how much bigger it had to be.