Minimal case for Cluster Triple

Minimal case for the [Cluster Triple](https://www.tindie.com/products/8086net/cluster-triple-for-raspberry-pi-compute-modules/) adds protection for the Compute Modules and keeps things cool with a fan.

For a single Cluster Triple case I used the following hardware.

8x M2.5 6 mm screw
4x M2.5 6 mm M-F spacer
12x M2.5 12 mm M-F spacer
4x M2.5 12 mm F-F spacer
60 mm Fan
60 mm fan grill
4x M4 Fan screws

To stack the second layer I used.

16x M2.5 12 mm M-F spacer
60 mm Fan
4x M4 Fan screws

I had a stash of M2.5 12 mm spacers, using longer spacers would probably make more sense if you have them. The screw holes are also sized for M3 screws (PCB has M2.5 holes so these need to be made a little bigger to accept M3 screws).