Cetus3D 40mm Fan Duc-Air distribution optimized

I made this part to replace the original fan duct, because the original fan duct cooling effect is not good.

I tested the original fan duct, although the original fan is not weak, but the cooling effect is still not good, because most of the airflow failed to reach the nozzle, but flowed away from the middle and upper part.

So I recreated a fan duct with a central and upper duct.

This version allows more airflow through the duct below, while allowing the airflow above to more effectivel