First of, I like this fan ducts very much. What I found out is, that the cooling is actually too effective for ABS prints and the layer adhesion suffers a lot from the efficiency of the cooling. I will be going back to a cooling with only one Fan but the duct has to compensate for it by going around the nozzle.
Thank you anyway for the design. If I could lower my rpm of my fans below 20% I think I would still be using this design