Fan duct for heat sink of FLSUN QQ series

This fan duct helps increase the cooling efficiency of the heat sink by at least 50%, by concentrating the airflow from the rear fan directly into the heat sink. According to my detailed measurement, the original setup has about 50% of its airflow bypassing the heat-sink fins (especially from their top and some from the sides), mostly due to the un-organised surroundings with cables/wires (see pictures).

This is actually inspired by the fan duck design of the E3D-v6. And it works better than I thought. This design is for the effector module of the FLSUN QQ series (QQ, QQ-S, QQ-S Pro, etc.). The pros include:

1. easy to implement: the printing time is less than 10 minutes, plus another 5 minutes for installation; for the installation, simply un-screw the rear fan, put in this duct, re-screw back the fan, and that's it;
2. totally reversible: you could get rid of it any time, especially when you decide to upgrade your hot end module including the heat sink;
3. it increases the cooling efficiency of the heat sink by at least 50%, dramatically reducing the chances of filament clogging near the top of the hot end;

No cons found so far. Please do let me know if you see any so that I could further improve it. I actually went through several iterations to achieve this version (as shown in one of the pictures).

After you print it out, you may want to trim or polish it a bit so that the airway side stays smooth and clean. In my case I don't need to do that and this depends largely on the materials you use and your printing parameters.