This is a remix from popular Semi-Circular Anet A8 Fan Duct made by lokster.
I just added the mounting brackets and measured the get it right, I didn’t change anything to the blower part except the top mount.
Print it like I put on the build plate, make sure not to print support in the blowers, see also my Cura settings screenshot, double check the supports before printing.
I also added 3 extra holes on the bracket, I use that to zip tie the cables. I didn’t like the cables hanging to Bowden tube. See pictures for reference.
Make sure that the nozzle heater wires (Power and Probe) not pushing the blower down, zip tie the wires higher, otherwise it will push it down and the blower will deform at back side.
EDIT: Print in ABS if you can, after a large surface print the PLA duct gets deformed with the heat of the bed and nozzle block. I might try to add a extra mounting point if I can find a place to mount on at a decent way.