After breaking the crayons into the mold, I baked them on a metal pan at 250 degrees for about 20 minutes. As soon as they looked entirely melted I pulled them out of the oven and let them cool. Once cooled, they popped right out super easily.
The next step involved gluing the hearts to a piece of card stock paper that said, "You color my world!". I used the hot glue gun, which seemed to do the trick nicely. The kids enjoyed the process and the Valentine's were a big hit. This inspiration came from Family Fun!