I remixed the multimeter storage mount I found on printables and made it wider in the multimeter portion to fit up to a 75mm unit, and also modified it to work with the DDD Wall Control system seamlessly. The original required M3 screws for mounting.

There are two versions:

-Thinner wall will have the 8mm pins able to protrude into the storage compartment by 2mm.

-Thicker wall version has thicker walls in the rear portion so the pins do not protrude and it adds a little strength, though the thinner version is plenty for this application.

I also chamfered the DDD mounting flats to match the profile of the multimeter mount, included in the print file. They are functionally identical.

I added supports, I find it prints the cutouts cleaner for the pins but that's just me.