--------------------- 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 spacing ( the closest one ). The square holes are provided to secure the installation with a zip tie around the cold part of the extruder. Solidwork file provided for mods. Enjoy and let me know ;-)