Baked marbles recipe: Put your clear marbles (It’s useless to use solid colored ones. You can’t see the cracks on the inside.) in a pie pan. Bake them in a preheated 500 degree (farenheit) oven for about 20 minutes. Have a metal bowl with ice cold water ready. Remove your marbles and immediately dump them into the water. The marbles crack, you ooo and ahh, and you’re done!