In case, anybody is interested, I made a quick and dirty design for a case for the CM3588 NAS board with 2x 40mm fans blowing across: https://github.com/sgofferj/CM3588-NAS-case
This is very nice.
Probably a hole for the power button on the front side and a hole for a small OLED display and that would be perfect. I am very noob for 3D modeling so I will just to try one case already existing.