materials: an iPod with USB cable (or anything that charges with USB) -battery holders that can hold 3 batteries (I used 2 duel AA holders and rewired one to hold one AA) -a female USB socket -a case (I used a mint tin) -something that can make a rectangular hole in the case
First, cut a hole that will snuggly fit the USB port. Slide the port in and tighten the hole by bending back metal, glueing or whatever you want.
Now you should make a chain of batteries. Attach 3 1.5v batteries together using the holders. You may have to improvise but this is what i have. DO NOT USE MORE THAN 5v OF BATTERY, this will fry the iPod.
Now you may connect the batteries to the usb plug. Now all you have to do is secure everything, I used hot glue. It not only secures but it also insulates.