Velocity Stack for 40mm fan
thingiverse
Quick and dirty elliptical velocity stack for a 40mm fan. This has just about the largest possible internal diameter (38mm) without needing funky geometry to fit the screws in (which disrupts the "smooth" airflow) Most of the other designs I saw were either too short for my taste or overly complicated without providing any real benefit, so I made my own version. Does this actually help improve airflow? Maybe. It definitely seems to reduce turbulence around the fan's intake side.
With this file you will be able to print Velocity Stack for 40mm fan with your 3D printer. Click on the button and save the file on your computer to work, edit or customize your design. You can also find more 3D designs for printers on Velocity Stack for 40mm fan.