Cases for Raspberry Pi 4B with POE Hat from Waveshare.
PoE HAT B with OLED screen or C without the screen.
Bottom and top cases snap together without the need of screws and/or nuts
https://www.waveshare.com/poe-hat-b.htm
https://www.waveshare.com/product/raspberry-pi/hats/interface-power/poe-hat-c.htm
Updates
The author marked this model as their own original creation.