.. this seems to me like one of the most interesting hotend builds i´ve seen - many thx for that!
started to change all fans, because the noise is absolutely awful - more than anything else. my main problem now is the radial stock fan on ender 3; this is also a very cheap and crappy one - makes lots of noises even on x-movements (already changed to new one - same story). but - i couldn´t find a proper radial fan available and since it is regulated, stepdown module for a 12 v version axial can´t be used. so i´m now trying the 5015 (also cheap crap?) version; if this doesn´t improve, i need an axial solution - maybe with a resistor (330 ohms, > 0, 5 watts should do) - anyway.
.. would be extremely nice, if you would develop a compact part version of "partduct" for a 40x40x10 axial fan in addition; could maybe be placed lying at an angle on top in the center to even distribute airflow more even, and - make the design even more compact. something like in the picture as just ONE possibility of many. ;-)