Minimal mount (back corner/side brackets only) for Ubiquiti Cloud Gateway Ultra.  4 small screws in the corner will be all you need to mount them, then slide the gateway in from the front. 

Mounting dimensions between holes - 3.8" deep, 5.4" wide.  

Benefits of using these vs. a full mount with cross-supports is that the printing orientation allows them to be strong laterally.  Also, you have a bit of clearance between the shelf and the unit letting it breathe. Will be pre-printing in Bambu translucent PETG.