The charger works with two lithium batteries CR2032 conected both of them
in serial so we get 6 volts and that its enough voltage to charge your phone.
Step 1: Materials
2.two lithium battery CR2032
3.two white leds
4.three pieces of metal
6.One usb micro plug
Step 2: Build it
With cutter you will need to make channels in which to put the wires.
Look the image below too see how are made.