I wanted to eliminate any barriers to airflow in murat's design, and since I've been using gijs fan duct I figured a combination of the two would be a good idea.
WARNING: This thing does get hot enough to warp if made out of PLA, but I believe that if made out of ABS it can be quite effective. Haven't tried that yet but it's on the todo list. Despite being flexible during printing the fan duct seems to hold up. We'll see how long until creep makes it useless.
UPDATE: Printed in ABS, actually handled the overhangs better than in PLA. The base warped a bit because my fan was going too fast so mounting it was very awkward. Managed to hack something together. Will test soon.
UPDATE2: Printed a hollow calibration pyramid (T:8757) using the new (bigger nozzle, made of ABS) fan duct, looks great! The best I've gotten yet. The next test is whether it will sag during a 10 hour print..
UPDATE3: been using the ABS version for three months now with no issues. It warped a bit initially because a portion of the nozzle touched my heater cartridge, but after mounting the heater cartridge properly it didnt warp further. Still works well!
Print without support. I used 0.16 layer height, 0.5 layer width with blue PLA. There are some pretty gnarly overhangs but it turned out ok. Ideally it should be made out of ABS though.