I have held off changing the fan duct on my Ender 3 Pro and Tevo Tornado until I could do some proper back to back testing. I took the chance to test the Bullseye and a simple vent ring duct.

To do this I designed a torture test file, inspired by the All In One micro printer test. The main body is lifted up off the bed to allow a wide and difficult bridge. There are four gradually tilted arcs, from vertical to 80 degrees, pointing up, down, left and right. The reason to see if a fan that only blows from one side is at a disadvantage. The final feature is a central spire that is raised above the rest.

My cooling fan torture test: https://www.thingiverse.com/thing:3167063

Next test might have to be the Hero Me..

Ender 3 ring duct: https://www.thingiverse.com/thing:2912394/
Bullseye (part of PETsfang): https://www.thingiverse.com/thing:2759439
What you need to print for Bullseye (Creality): https://docs.google.com/spreadsheets/d/e/2PACX-1vS2TxsX-kBR6hmoeuBAtugCa8P2651bOPuQJ76QD8jk-UFWg4FWrNI2Ca36mKzLy2FUOWA…

My complete training:
https://www.udemy.com/blender-279-complete-training-from-beginner-to-pro/?couponCode=BLENDERMASTER9

3d printing with Blender training:
https://www.udemy.com/blender-279-discover-3d-printing/?couponCode=PRINT10

Reference Image:
https://www.dropbox.com/s/5uf9jxxlmj7y2mb/piece%203d.zip?dl=0