If your child likes to play with colored dough but you're out of the brand name stuff, try making it yourself. Here's a recipe I use in a pinch:
-2 cups flour
-2 cups water with your little one's choice of food coloring
-1 cup salt
-2 Tbsp. cooking oil
-2 tsp. cream of tartar
Combine the ingredients in a medium saucepan and stir over medium heat until it thickens. I find it stores best in an airtight container in your fridge.