PrintrBot 50mm Fan Cover
This is a remixed part which started at 60mm and is now at 50mm.
This fan part is specifically measured to fit the front of this part:
http://www.thingiverse.com/thing:671220
This will NOT fit the printrbot fan that comes with the printer. If you are looking for that, go here:
http://www.thingiverse.com/thing:261115