Inspired by https://www.thingiverse.com/thing:2843889
I used the one linked above for the Pi3, but needed an upgrade for Pi4 and decided to use a noctua 40x10 fan, as the new raspberry runs a little hotter.
This can be mounted on any side of the MK4/MK4S/MK3/MK3s printer. I chose to put it under the einsy board box.
The fan is mounted with screws that came in with it, and the case is held together with four m3 screws.
It's a tight fit, but works for me :) Also, I forgot to add the opening for the status LEDs…
When printing, flip it flat side down, this way no supports are needed.
Thingiverse:
https://www.thingiverse.com/thing:3901483
The author marked this model as their own original creation.