A quick 40mm remix of the Prusa mini power adapter holder by Skov Knudsen Inventions with an added cutout. I use these to mount my power strip under my IKEA LACK Prusa Mini enclosure. It may not be the absolute perfect solution for my scenario, considering that the plate is hollow etc. but I like the idea with the two corner brackets only and it works just fine for now.

I just quickly changed the height from 35mm to 40mm, added a round cutout to not block the sockets / power switch, and printed 2 of these with PLA (no fitting PETG at hand) at 0.35mm layer height (0.6mm nozzle), 25% infill, and support (75% XY separation, 3mm spacing, don't support bridges).