Extruder fan (50mm) for Printrbot Simple Metal

This is a no-frills mount for a low-profile 50mm fan for the Printrbot Simple Metal 2014, to keep the extruder motor cool. Holes are sized for countersunk self-tapping screws (the standard type that comes with PC fans. There's no fan guard.

A 50mm fan fits perfectly here. A cheap source of 50mm fans are 3.5" hard drive coolers, which feature two of these fans, and costs the same or lower than trying to buy a standalone 50mm fan.

I found that I had to rotate my bed sensor to accommod