The Raspberry Pi 4 really benefits from a heatsink. I got this cool Aluminium Extrusion heatsink case for the Pi 4 from Pimoroni for £12. Lots of shops sell them including Pi Hut and Adafruit, some places call them "Aluminium Armour heatsink case".
I designed a couple of quick upgrades to the case. A cover and protect the GPIO pins (I'm running Octoprint, so I'm not using the GPIO) and a clip on cover to tidy up all the USB & Ethernet ports.
You got the 3MF files for printing and the Solidworks files (these are made on an educational licence.)
Photos show the case with and without the covers. I've based all the tolerances on measuring the one case that I bought from Pimoroni. It works on mine, If you find this is out of tolerance for yours, try scaling it up by a few%. Please send me the dimensions and I will be happy to modify the files.
I'm printing in PETG. Pretty much any standard settings should work, they are easy to print parts in under 1 hour.
Edit: Thanks to borken@borken_206183 for pointing out that the USB cover will fit a Pi 3 if you mirror the part.
The author marked this model as their own original creation.