I took the amazing 19inch Rack from boxes.py (https://www.festi.info/boxes.py/Rack19Box?language=en) and made a pi-rack-mount out of it. On my pictures i have space for one pi3 and three pi4's. In the svg there is my version, a version with only pi3's, only pi4's, and two pi3's and two pi4's. You only need to laser the one front plate you need.

The hole on the front plate on the right of the pi's is for cables you need to plug in the pi. I have two 2.5" hdd's in the back of the case.

The Box is made for 3mm plywood, but mdf and acrylic will also work great. I think clear acrylic would look amazing, but i sadly had nothing on hand in that size.

I have also included the stl for the fan mount i have on the pi's on the pictures. It holds 30mm fans. You don't need them, but they are nice to have and fast printing.

Have questions? Feel free to ask me, i try to answer them fast.

Have fun with it