I tweaked Puttelino's fan mount so it fits the standard Printrbot Wade extruder better and added a couple of supports to make it a little stronger. Be sure to grab the funnel part from Puttelino's design, it works great.
Use ABS for heat resistance from the extruder and a high fill for strength. You'll probably need some cooling to make it look nice or print two of them. It's always good to have a spare!