Dual fan cooling duct for Flashforge Creator/Replicator dual

Newer version here: http://www.thingiverse.com/thing:1270858

This is based upon MasterFX's design but with some notable changes. Instead of the airflow directed downwards, it is directed across, aimed right at the tip of the nozzles.

No supports required for printing.

This duct clips securely onto the extruder assembly using no fasteners. The single fan provides for a nice curtain of air flowing across the print. Adding another fan or a larger fan would serve no useful purpose because