How to make Christmas ornaments out of old crayons. Preheat oven to 250. Peel the paper off the crayons. Place pieces of crayons in muffin molds. Melt crayons in the oven, about 10-15 minutes. Remove from the oven. Add an ornament hanger to the top. Allow ornaments to cool and harden inside of the molds. Once hardened, remove the ornaments from the mold.