3Dator extruder with cooling duct

I'm very fond of this extruder design so I decided to make some improvements. The original design is capable of pushing filament with great force albeit this requires the stepper to be driven with high current. Increased current means that the motor heats up and the heat is dissipating through all parts of the motor, including the axle and MK8 wheel which eventually will make the filament softer and deform causing feeding failure.

With the adding of the coling duct and the rear fan mount the