2 c. baking soda
1 c. cornstarch
1 1/2 c. cold water

Mix soda and cornstarch together. Add water, stir until smooth. Cook over medium heat until stiff like mashed potatoes. Pour out on floured plate, cover with wet towel until cool enough to knead. Knead and roll out to 1/4 inch and cut with cookie cutters. Let dry. Use food coloring to color or paint with felt pens.