And I really got fancy later, and started making these out of 12x12 scrapbooking paper. They ended up way bigger, because essentially, you need a square piece of paper to make these.
We used scrapbooking paper and some old decoupage paper I had from a million years ago, and it worked pretty well. I didn't have enough cardstock to use that, but I think it would probably hold its shape much better.
I have a couple more heart/Valentine's projects saved up, so stay tuned. I kind of like this blogging stuff. :)