Rusty Tin Candle.

[Ilona]

Just mix equal parts of bleach and vinegar (outside!) and soak the tin in it.

If you want to speed up the process, add a small piece of already rusted tin to the mix.

Hope that helps!

It's not really a secret method. I learned it in high school chemistry class.

As for sharp points, you can use one of the new can openers that leaves safe edges. I forget what they are called.