A wall holder for two ER40 collets. 

The design Includes spaces for 18mm wide marking tape from a label maker, but you can write there with a good pen as well.

I made these to organize the ER40 collets we use in our ZX45 mill at Stockholm Makerspace

The mount is made to be mounted with two truss head screws, and there are holes in the holder to get in with the screwdriver to tighten them down.