Fell in love with the original thing I used (https://www.thingiverse.com/thing:2547462) and decided to take a stab at a remix after I put my Raspberry Pi 4b to use. Referred to the mechanical drawings for the Raspberry Pis and the decora plate.

The 1U rackmount bracket I am using is from ebay (https://www.ebay.com/itm/264097865148) but you should be able to use any decora bracket.

The face plate named decora_rpi_3b.stl will work for the Raspberry Pi 5 (pictured), and I confirmed that the official Raspberry Pi Active Cooler installs without any clearance issues.

The face plate named decora_rpi_3b.stl should work for the Raspberry Pi 2, but it didn't fit the Raspberry Pi B+ I checked.

I wanted the tolerance to be pretty low, but I only have one Raspberry Pi 4b to verify with. Please let me know if you have issues.

Use four M2.5 x [4, 6, 8] if you don't want the bolts to extend beyond the bottom of the base. I had to create the threading for M2.6 on the mounts to avoid tapping.