Note: Design still underwork for further optimization.
if you try it please leave a comment with any suggestions or improvements.
This fan duct is for E3Dv6 hot end and 40mm cooling fan. Most of the air flow will go to the hot end, while the rest will be channeled to the nozzle for the print coolling.
Use a fan with enough airflow as it will work as two fans in this case.
if you have any issue to make the duct fit your hot end try heating the duct with hot air gun or even a lighter and tighten the hot end holder a little. I made the radius 22.6 which should be a tight fit.
Note: i didn't have a chance to test the performance yet, use this design on your own risk !
Update: After testing the mount with silent fan (0.05A current) it leads to filament jam if not while printing it will be hard to change the filament. Those have lower airflow, so I put a more noisy fan but 0.15A current and the results are amazing. My printing quality improved significantly, I tried it on regular APA, Carbon fiber PLA, and ninjaFlex.
Rotato -90 degrees on the Y access before printing.