Simpler 40mm fan mount

This is a simpler version of an existing 40mm fan mount found here. When we first got our printer running, there were no fans blowing directly at the extruder and the original design had a hard time printing cleanly.

This is a simpler version which should print just fine without fans or supports.

I updated the original design with Blender, so the .blend file is attached.

It attaches to the fan mounts on the X-Carriage (http://www.thingiverse.com/thing:18657).

We ended up with a 10mm thick fan and a standard 20mm thick fan on either side of the extruder.