Fan duct NineStars

Original Satsana fan duct is a good design but not well optimized.

Actually, the Satsana upgrade is less efficient than the original metal cube from Creality.
The fan blows the upper part of heatsink. Which does not cool the filament inside well and augment stringing.
This remix redirect the fan right against the heatsink to make it more efficient.

Also, holes are a bit wider to make it more easy to screw and there is a small gap to pass wires from the fan easily.

The experiment to estimate the efficiency of this upgrade is to measure (several times) the cooling's delay from 185°C to 100°C :
Creality : 1m39s
Satsana : 1m48s
NineStars : 1m18s

NineStars's fan duct remix is much more efficient