dual 40mm fan duct for direct drive extruder

This is a dual 40mm fan duct for my direct drive extruder, you can find [here](http://www.thingiverse.com/thing:750801).

Parts included in this design can be seen as white parts on the picture.

Note: The hotend must be mounted with the heater facing the x carriage. The back part of the hotend is needed as a flow obstacle.