Wanhao Duplicator i3 fan duct for 30 mm and 40 mm axial fans.

thingiverse

EDIT: New Ducts. TAHfan15 is a top-notch front duct for 40 mm fans, delivering outstanding performance with its robust fan. TAHfan16 serves as a reliable rear duct for 40 mm, designed to be securely attached to the backside of the bottom bearing block via a single M4 x 10 screw. Its seamless integration with TAHfan15 offers unparalleled double coverage. Personally, I prefer using TAHfan16 independently without a front fan, allowing me to better monitor the printer's operation. TAHfan17 is a cutting-edge front duct tailored for 30 mm fans, exhibiting extraordinary airflow thanks to its expertly crafted channeling and larger inlet. This model outshines the stock duct in every way possible. OLD: I am exploring an innovative approach with this design - a straight duct that effectively envelopes the hot end by more than 180°. Additional development is underway, involving a rear duct attached to the extruder. Although still in the testing phase, preliminary results demonstrate its potential.