dual bowden extruder carrier for reprap cube 3d printer

this is a extruder for my reprpap cube 3d printer. http://www.thingiverse.com/thing:13954
it consists of a central slider and carries two hexagon hotends.
there are two 25mm fans for the hotend cooling and two 40mm fans with fan duct for the extrusion cooling.
more information on www.robotik.dyyyh.de
the upper part, where the hotends are plugd in is a milled aluminium part for extra cooling. i have not tried, but maybee it can be printed too.