Gridfinity End Mill Holder

This might already exist, but I couldn't find it. This is my contribution to the lovely gridfinity box universe [GBU]. Specifically made to store end mills, these boxes are standard 1width X 3length X 1height units with cutouts to hold those odd half inch (version A) or odd-almost-half-inch-but-not-really-half-inch-is-this-metric-why-can't-I-find-out-what-size-these-are (version B) end mill plastic containers. I generated a solid box by using the SCAD web generator, and then modified it to hold