Extruder and stepper cooler. Sends some air through duct to filament drive gear.

The idea of uber ventilation is to keep the filiment cool and prevent it stripping. The sides of the cowel allow the air stream to stay near the stepper.

If this works well then it'll be time to print it in glow-in-the-dark ABS and apply some UV LEDs.

Print all 3 bits.

Assemble.

Done.

Takes 2 of the 17mm bearings with 6mm centres and a 60mm fan - mostly because I had a quiet one laying around.