Wall Holder for File Set

I got a set of little files for Christmas, but they didn't come with a case or anything. Threw this together and decided to use it as an excuse to learn scad files that work in Customizer.

The screw holes are designed for "size 6" wood screws. I have no idea what that means, but the heads are countersunk, 6.5mm wide at the top, and I was able to find a package of them in an american grocery store.