This is a simple mount / holder I designed for my 4-channel relay module (ELEGOO brand). The relay module is attached to the holder via 4 M3 screws (exact length doesn't matter much). I strongly recommend printing out of UL-certified self-extinguishing filament (such as Prusament PETG V0) for safety, though other materials could technically work.
The author marked this model as their own original creation.