This is a remix of http://www.thingiverse.com/thing:1228237 and I have (rather shabbily) added extra room for better air flow and increased printability. The old version was somewhat of a pain to print because of the large unsupported middle section. Also, the back middle air hole on the old design forced out too much air, so I reduced the air flow to that area by putting a support column in the interior.
The infill is somewhat irrelevant, it can be whatever you want. Recommended to print in ABS so that it won't droop and drag on top of your prints.