cooling fan + duct dual extruder

--------------------- EDIT -----------------------
The last STL provided does not match with the photos .
The lower part has been redone in oder to adjust the air flow at the tip of the hot end.
The separation between the 2 nozzles has been deleted.
Solidwork file attached accordingly.
---------------------------------------------------

designed for the excellent dual extruder from Riku Rusanen http://www.thingiverse.com/thing:201184.
The design has been done for the 20.50 mm spac