Make your own small fan that can rotate without plugging in
You can make a hand-cranked one, or you can use a clockwork to convert elastic potential energy into kinetic energy, or use recoil to For example, the air jet from a balloon drives the fan blades to rotate
Find two gears, one big and one small. Install the small one on top of the fan. Insert a hand crank on the big one and use the big gear to drive the small gear. In this way, you Shake it slowly, and the fan can rotate faster (you can find some ready-made gear combinations, and all you have to do is install the fan blades on the gear shaft)