This person who made some Halo 3 Sushi did a great job. Makes me wish I had some to eat.
Aluminum air batteries are supposed to have the highest energy density of all batteries, so why not make your own and experiment.
Paper Towel Soaked in Salt Water
Activated Charcoal/Carbon (found in the aquarium section at stores)
Voltmeter/Lamp/Something you can tell you're making voltage with