Blow-Powered LED Flashlight
A mechanically powered flashlight is a flashlight that is powered by electricity generated by the muscle power of the user, so it does not need replacement of batteries, or recharging from an electrical source. There are several types which use different operating mechanisms. They use different motions to generate the required power; such as squeezing a handle, winding a crank, or shaking the flashlight itself. These flashlights can also be distinguished by the technique used to store the energy: a spring, a flywheel, a battery or a capacitor.
(https://en.wikipedia.org/wiki/Mechanically_powered_flashlight)
Now, I made a blow-powered LED flashlight. To turn on a flashlight, you just blow (to force air out through your mouth) it.
The only bad thing is that if you use it too much, you will be dizzy ( just like blowing a balloon too much).