This fan cover is designed to work with the 40mm Noctua fans, both 10mm and 20mm high. It will probably work for most other brand fans though. This is purely for aesthetics, as I didn't like the beige colour of the fan body. I didn't make a grill as I didn't want to restrict airflow, but I will probably upload a version with a grill. Especially if there's some requests for it.
This has a 0.2mm tolerance around the fan body, providing a loose friction fit. The screw holes are purely for access, not to hold it in place. There's a small notch on one side for the wires to come out. The thickness of the part is 1.4mm, so I recommend printing with 0.35 line thickness with no less than 2 shells. I printed it with a layer height of 0.175mm. I also recommend printing this upside down, so you don't need any supports.