Several years ago I made a case for four motherboards. http://coyoteridgeobservatory.blogspot.com/

It is similar to the Helmer Render Farm. http://www.helmer-air.com/ It is larger, breathes much better and is much quieter with the larger fans.

That cluster project has morphed into many other things and the case is now for sale. Motherboards, CPU, memory, power supplies, etc. not included.

Case with power buttons, LEDS, $100.