Imagine, any AA or 9v battery could charge your phone and other USB gadgets. Behold, the LM780!
This is a voltage regulator chip. Stick between 5 and, say, 9 volts in one end and huzzah! (about) 5 volts pops out the other end. these cost a few dimes and can be had on ebay 10 for 4$.
Below is the BOM: (to make 10 chargers!)
Then arrange them like so:
...Notice I squished the power wires under the bent pins. RED GOES TO THE PIN ON THE RIGHT when facing the shiny side, and BLACK GOES TO THE MIDDLE ONE.
...The remaining leg is attached to the far left pin on the USB port (when facing the chip's shiny side remember).
Then it works!! YAY!
Here I verify it works by charging my commercial usb charger with my DIY duct tape one: