Simple dual bowden Extruder for Prusa i3 rework

Update:
--> Tested and working flawlessly, no issues with cooling and airflow.

an update under works: light rig setup under the fan

I had the following Design goals:
-single fan, enhanced airflow duct to maximise cooling and reduce fan noise.
-using common E3D extruder body and alu heatsink
-Keep minimum distance between heads (now at 24mm), still need to work on parametric approach (which started with 40mm).
-easy to disassemble (you know, jamming/cleaning and so on). Due to