portable battery fan

Portable battery fan.
Powered by either a single 18650 battery or a 5V source.
Has three operating speeds.
A fully charged 2500mAh battery operates for about 5 hours at maximum speed.
The control board used charges the battery itself, monitors its health and has overload protection in case of accidental blocking of the fan.
The electric motor used has reliable brushes that do not burn out when the fan jams.

I tested several propellers taken from the sources below.
https://github.com/RaulBejarano/Ultimate-Toroidal-Propeller-Generator
https://www.thingiverse.com/thing:5300828/files
https://www.thingiverse.com/thing:3874607

Unfortunately, I was not able to make a silent propeller. I would be grateful if someone more experienced in aerodynamics than me could make a quiet propeller for this fan.

The fastening of the two parts of the fan to each other is borrowed from the modular system from here https://www.thingiverse.com/thing:2194278

Printed without supports, does