Just melt and pour into metal cookie cutters.
Step 1: Unwrap all paper from crayons (that you will be melting)
Step 2: Place crayons in a tin container or old pan (or old hot pot). Tip: Try to keep light colors together. If you mix light and dark colors, the color of the crayon will turn out dark.
Heat in over or on stovetop.
Step 3: While crayons are melting, place metal cookie cutter on an old baking pan or platform that you won't worry about. Roll out a little play doh (the size of the cookie cutter) and gently push the cutter into the playdoh (this will keep the liquid from running out)....do as I say, not as I do. I learned this tip from experience.
Kids love these. What a great way to get some extra mileage out of old crayons.