I made this simple set of racks that I use to place my modem/router/Apple TV, etc.

The size is 220mm x 160mm

They are attached with 10x2mm magnets

The “base” model uses 4 magnets (4 at the top)

The rest uses 8 magnets (4 at the bottom, 4 at the top)

I print them upside down.

For the non-"base" models, I use tree supports for the leg overhangs.

p/s: If you require different size and height, do let me know!