Gridfinity Endmill Holder (32 slots, 3x4)

What it says, takes containers up to 13.5x13.5x70-ish millimeters, that covered all that I had at hand.

I use this for new endmills and keep the ones currently in use in the endmill tray you can find in my uploads. The design goal here was mainly to be able to see what endmill is in any given container at a glance. 
I orient the label to the back, if you did orient it to the front, the container/endmill in front may cover part of it. But then again, I suppose most of us don't have that many variants of endmills with differences so small you need the label to distinguish them.

As for printing without supports: YMMV.
Wasn't designed to be printed without, but standard support material was easy enough to remove.