I have a mini PC I use for running several services on proxmox which should be placed somewhere out of sight. Easiest approach is to hang it on the wall with only power and network connected and one screw is good enough then to keep it simple.

So, I have designed a strong, but pretty simple frame, which is fast to be printed (I have used PLA here now). It perfectly fits on an older refurbished HP Elitedesk computer, which has a 100 mm x 100 mm VESA frame preparation right on the case. Thickness ensures enough air ventilation behind the case.

Print it, screw in on the computer and fix it with one screw on the wall. Done.