Created some additional mounts for the 19cm Rack, following the original dimensions. Except for the Optiplex Mount they all hold themself and have locations for the originally designed wallmount screws. For the screws I used M3 buttonhead, tapping directly into the filament as they are more guides than really hold any weight. Just keep stuff from moving.

For the Optiplex, I used one of the wire plates from this great remix at the back to support its weight: 19cm network rack additional mounts von dmuva | Kostenloses STL-Modell herunterladen | Printables.com For a more solid mount like the others would be more space needed as the 3080 fits just in there. 

The Mirkotik Mount also fits the standard Hex, though the USB port is not accessible in the current version, as there is no fitting cutout. If you dont use the USB port, it should also fit every device with the Hex-Based case.