Update 2024-09-01: Added a model with a frame 3mm thick.

I have an air duct above my computer desk In the basement suite I live in and one night while working on another project the metal vent cover fell out and hit me in the head. Thus after 4 hours of getting things right, I made this plastic replacement that I could tape in place as a lighter replacement.
This design is not perfect and may not fit your vent, please measure and compare before printing this design. This design pushes the air at 45 degrees in one direction to divert the air from where I sit. It does not do both directions.
For my use case, I printed the design in PLA at 20% infill on end as the design loads into your editor (I use cura).
Feel free to modify the design and edit out my username that appears on the one side.

Ender 3 Pro

Yes

Yes

0.28

20%