Summary

Original by ckaos.

The original wasn't quite complete so I added some options and fixed the default layout.

Instructions

OpenSCAD file attached so you can roll your own.

Reduced the duct. The fan will move enough air.
No duct so I don't think you need the capacitor hole. Made it optional.
Mirrored Top to fit properly.
Added option to put holes in the top so you can bolt it together. I used zip ties and haven't reprinted this with the holes. I think the idea was to snap fit but mine won't stay together via friction. There might not be enough headroom depending on your specific components.