This was posted on pinterest and I thought I'd try it out since I already had the oven on for dinner.
Marbles in the oven at 350F for 20-25 minutes, rolled off tray and into a pot of cold water to create a crackle in the inside of the marble.
"Mommy, why are there marbles in the oven?"
"what are you doing with them?"
"can I have one?"
"are they gonna explode!?"
Pot in sink. (I did think they were gonna explode too)
we could hear the little crackling sounds of the glass inside the marble. It didn't happen all at once, it continued for a few minutes.
I just think I need more interesting marbles if I'm going to make a necklace or something out of it.