When I was a kid I used to love making melted crayon art on my mom's 70s-style hot plate. There's just something magical about how the wax spreads and creates such vibrant colors. Plus, it smells terrific! I went looking for how to make melted crayons without a hot plate so I could share that experience with my kids, which is how I discovered melted crayon rocks. Of course, you can create these rocks in a rainbow of colors, but we decided to make a set in red, white, and blue for Memorial Day. They're handy for weighing down napkins and a picnic, and they make great paper weights.
One important note: This project requires close adult supervision. ALWAYS check and make sure the rocks are not too hot to handle safely before decorating.