http://www.****blick.com/products/am...ex-white-clay/
http://www.****blick.com/products/am...-clay/#reviews
Non-toxic and looks/feels like stone.
Can be tinted any color with non-toxic pigments.
I've considered it myself.
They'd probably 'hold heat' just as well as the clay flower pot hides some keepers use.
I was worried it would 'dissolve' if it got wet but I had a box of it accidentally get exposed to air and no matter how long I soaked it, I could not 'resurrect it' to usable, pliable clay again.
It gets really hard.
You can also bake it and seal with non-toxic acrylic sealer.
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