PrintrBot Simple - Hinged Extruder drive fan mount for 40mm fan

This part is based on the excelent http://www.thingiverse.com/thing:82533, it fixes a problem for me, where i need a small fan on the side of the extruder to keep the incoming pla filament cool and stop it from softening when heat creeps back from either the extruder motor or the hotend. This tends to cause the PLA to soften and it buckles and jams.

I did not want a fixed structure as i still need access to the cavity to fiz jams.

The solution was a little trinket box, altered to make it