Supplies: Pencil, copper wire, 6V Battery, Crayon, Metal Tin, Medium Plastic or Glass Container, wires with alligator clips attached on both ends, Acetone (Nail Polish Remover), sandpaper (if using an altoid tin or other tin with design and/or color on it), salt, and water.
Your supplies can all be bought at your local store like at Walmart. That 6V battery, I found in the camping department (they use them for lanterns). They are about $1. The wire and alligator clips can be bought at Radio Shack. They are about $3.
You could use Altoid tins, however, I bought a huge supply of plain tins, as I’m using them for many things. If you have Altoid tins you will need to sand off the design on the top (or anywhere that you want to end up etched), using sandpaper and lots of elbow grease!
If you buy tins from a hobby store that are like mine, you will still need to remove a protective layer they all have on them. You can remove this by using acetone (or nail polish remover). Make sure you remove all of this protective layer because the etching will not happen where any of that protective layer is left.