The secret to getting a good punch without crushing the can is to freeze water in them overnight, when you're done you just run it under warm water and out comes the ice. Also, freeze an inch of water in the bottom first then fill it up, now the bottom won't bulge out. The towel was to set your can on to catch condensation and keep the can steady.
Carroll brought several of his own luminaries to show us.
One was even done in a large popcorn tin. Very cool!
I took a picture of mine outside in the dark. I think next time I'll choose a little less intricate pattern or maybe less holes. It's a butterfly with a swirly tail.
A big thank you to Carroll for sharing this technique with us. It was fun!