Here is a remix of a fan guard that I downloaded, printed, and used. Thank you, @nixkor. I admired your design for its simplicity, elegance, and as you mentioned, its high flow. Inspired, I wanted to make some modifications, so I redesigned it incorporating the changes I envisioned and now present it to you as a remix.

The two main modifications I aimed for were the inclusion of countersunk screw holes and an enlarged gap between the guard and the fan blade. Additionally, this model is 1 mm taller than the original. Notably, the way I designed the countersunk holes allows them to be printed upside down without the need for support material.

Although the original design wasn't noisy, I noticed a faint whistle, which I attempted to mitigate by introducing a 1 mm gap between the fan blade and the guard's profile. Moreover, I added chamfers, believing that sharp edges might worsen the whistling.