It's been a long time (over 5 years) since I last designed the Multi-pi stacking case and with having two new Raspberry Pi 4's I decided to break out my design skills once again...
So please let me introduce my brand new Raspberry Pi 4 cases (see attached images).
They've got lots of air vents and can take a 40x40x20mm cooling fan on the inside (currently using a 40x40x7mm).
My 4B4G is currently overclocked @ 1900MHz and is sitting @ 56c (idles in the mid 40's) and never goes over 60c - I'm only using a slow fan in conjunction with a heatsink.
Hope you like the designs.