Full explanation Clay Dough. Looks like porcelain. 2 cups baking soda + 1 cup cornstarch, add 1 1/4 cup water. Mix well, bring to a boil stirring constantly on medium heat. The watery mixture will thicken and then suddenly take the consistency of mashed potatoes... take it off the stove as soon as it does, dump it out of the pot onto a cookies sheet in one lump. Once cool, it is ready for play.