I’m sure many of you are already aware of this, but Canadian pennies up until 1982 were pure copper.
They measure about 19 mm x 1.4 mm and are very readily modified by filing, beating with a hammer, or simply putting on the railroad tracks like we did as kids. (They also have $.02 worth of copper in them, which is why they quit making them I suppose.)
You can also visit your local plumber and ask him if you can grab a few pounds of his clean copper scraps for the going scrap price.
According to wiki,
American pennies before 1982 are 95% copper.
Canadian pennies before 1997 are 98% copper.
Some people have hoarded the American pennies, so they are harder to get now than you might think. I don’t know if that’s the case with Canadian pennies.