To make this work, you'll need either:
or you can buy a hand-cranked flashlight from ebay for a buck and change. This method is prefereable for a couple of reasons. First, the cranking mechanism is far superior to probably anything you're going to make and will really torque up when you crank it, delivering energy to the battery and straight on through to the powered device. Second, you'll have a tiny motor and small battery already included for probably what you'd end up paying for the battery alone, so splurge and buy one or two (I bought two) hand-cranked flashlights. You'll be glad you did.
For both versions you'll need the standard tools: wire, wire snips, soldering iron, etc.