This case for my Octopi mounts to the back of the Lack enclosure. It has openings for USB-C and one of the USB-A ports, the SD card, camera ribbon cable, and a cooling fan. I also printed a set of Lack enclosure parts for the right side leg so I could pass wires through that side as well. 

Hardware needed:

(4) M3 x 8 screws to secure cover(or longer, up to 14mm)

(4) M2.5 x 6 screws to mount Raspberry Pi

(4) M2.5 screws to mount fan, length depends on your fan

(2) #10 wood screws, at least 1" long to mount case to Lack enclosure, or your own similar solution depending on your needs

* I like to tap holes rather than use nuts, so two metric taps will be needed (M3 and M2.5). I can remix this to use nuts if there's a need.

I printed this in PETG with supports under a few key areas, 0.2 mm quality, 50% infill