The fan is held to the wall with VHB tape and it's very strong and will not move. The good thing about this is it will work on any size fan.

Update: I have added a version to screw into the wall instead of using VHB tape just in case you'd prefer to go that route.

Maybe this will fit your needs as it did mine.

My print settings:

Material: PLA

Perimeters: 3

Infill: 15% Triangle

Layer Height: 0.2