I took all their old crayons & pieces and put them in a mini muffin tin on the lowest heat setting (mine is 200 degrees) and cooked them long enough until all the crayons were melted, but make sure you don't leave them in too long otherwise they may burn on the bottom.
I took it out of the oven & put the muffin tin in the freezer to help cool them down faster since I was waiting to do my second batch. You can also leave them out on the counter to cool if your not in a hurry.
They just popped right out of the tin when I took them out of the freezer. I tried to mix the lighter & darker colors together to make some cool color combos.