Printrbot Play Upper Fan Duct

Created from scratch in 123D Design (file included), but inspired by [Ubis 13s fanshroud](http://www.thingiverse.com/thing:1295731) by joeflush, this fan duct fits perfectly behind the fan when you use the [Printrbot Play Replacement Cover](http://www.thingiverse.com/thing:1271011) by crazyg0od33.

If you use longer M3 screws instead of the stock plastite screws, they should go all the way through the fan and into the duct for a more secure hold. Optional, but I did it on mine.