Hi there,
Using this: https://www.musicstore.com/en_DK/DKK/DAP-2-HE-Rackblende-f-Modulsystem-10-Segmente-MP-1/art-PAH0017160-000 modular 2U system, also called MP-1
You can print this and screw into it, to have a nice neat 1U unit for your Raspberry Pi's and other stuff you and others might design. You only need 2 M3 screws and 2 M3 Nuts to screw the Raspberry Pi into this model.
Krapozok had the idea for Raspberry Pi 1, 2 and 3 on Thingiverse. Mine is created from scratch for Raspberry Pi 5.: https://www.thingiverse.com/thing:1793758
Also available at makerworld: https://makerworld.com/en/models/146102
The author marked this model as their own original creation.