My original post is one prusaprints.

This fan cover has some depth and a spiral pattern both will help reduce noise often associated with fan grills. There are two version, this one for the fan that came with my ender 3 and one for the fan I got from amazon. There is also a freeCAD file on the OG post that has a spreadsheet where you can edit the peg diameter and length to customize it for any 4040 fan that has two free holes.

**To install **You take out two screw, top right and bottom left, then press it on.