In a saucepan, boil salt and hot water.
Stir cornstarch and cold water together in a separate bowl. Once the cornstarch dissolves, add this mixture to the boiling water. Whisk constantly
Reduce heat to low and cook until mixture is a stiff dough. Make sure to stir constantly so it doesn't burn.
Drop dough onto table and, once cool, knead for 5 minutes until firm.
Roll out the dough to about ¼ inch thickness and cut with cookie cutters (just like you would cookies).
Store extra in a plastic bag for up to 3 weeks.
You can let air dry for 48 hours (in a dry, breezy location)
Preheat the oven to 200 degrees. Bake on a foil covered cookie sheet for about 1 hour
Paint with acrylic or tempra paints. (acrylic cover better, but don't wash out of clothes)