Step 1: The Parts
You will also need: two super bright 5mm leds (I'll be using 15,000 mcd white), 2 led mounts, 2 CR2016 batteries, a coin battery holder, and some wire.
Not pictured: You will need a switch to turn the light on and off. You can choose a toggle switch, slide switch, or a push button. Again, this is largely a question of aesthetics. You should consider though if a momentary switch or an off/on type would best suite your needs. I chose an oversized push button that does both.