This is my take on a case for the Beaglebone Black single board computer when it is outfitted with a CRAMPS cape. I have one of these setups on my delta printer and will soon have one on my Mostly Printed CNC machine (http://www.thingiverse.com/thing:724999) build. I have designed the so that it can be fitted with a standard 80mm brushless DC fan. The U shaped hole on one end is to route wiring through. I am also uploading the Freecad files for easy modding. Pointers on how I can improve my gawd-awful CAD skills are appreciated but complaints are not. It prints out well on my printer.
Custom Trestle Delta 3D printer
Infill percent shouldn't make a big difference but you should use supports. I printed mine using Cura with supports "Everywhere".
Designed in Freecad. Make model, slice model, print model, go back to Freecad and fix mistakes, repeat until close enough.