Welcome witches and wizards!
This is a small part which you can clip to a hat (I hope nearly every hat) to mount a 40mm x 40mm 5V fan, which you can connect to a 5v solar panel or a battery.
I printed it with my Ender 3 S1 with 0.2mm layer height and 100% infill for maximum stability.
Watch this video to see how I used it, of course you are free to use it otherwise!
In the video description you will also find a list of the parts I used.