Nails (zinc coated)
Alligator clips with wire
Scrap copper wire
No film canisters? You can use a cup with plastic wrap over the top. That is the way we did it the first time. Works almost as good. We also sell the film canisters at catsscience.com
but you maybe able to get them cheaper from e-bay.
No alligator clips? We used old speaker wire that we found. It works fine.