I liked the design a lot, but I rarely use dual extrusion or my left extruder even. So I changed it to only allow the air to push through the right side! As a result it pushes even more air through the side you want, instead of wasting it on a extruder that is not running,
I used the right side and it work's GREAT but I will include a left side version for anyone who might print with that side. Please share if you make one.
Please refer to the original for instruction's, here - > https://www.thingiverse.com/thing:537918
Download the ACF-Right for the right nozzle, left for the left nozzle.
I could not get netfabb to repair the left version, should still print fine. Will try again later. Right side is fine.