New! Version 2 available here - http://www.thingiverse.com/thing:2227907
The MakerFarm Prusa i3v comes with a 40mm cooling fan and the E3D-v6 comes with a 30mm fan, so why not use both? This duct uses the 30mm fan to keep the hotend cool and the 40mm fan to cool the material!
This is version 1, I will likely do another version in the future with a more directed material cooling nozzle, but for now this will have to do!
Use ABS. PLA will be too brittle and will likely break when you snap this piece onto the E3D-v6's cooling fins.