I uploaded design files for my kosmo case. It was designed in Fusion 360 using parameters that can easily be updated to change the size of the case and be adjusted for the thickness of material used. It was designed to be cut from 12 mm or 1/2 inch material on a CNC router. I used 12 mm baltic birch plywood for my first case. It is a simple design, and could probably use a better design for the rails, but it does work.
I also added some stl files for some spacers I made to mount the AI Synthesis power supply board and power distribution board in the back of my case.