Make Watercolor Paints - baking soda, vinegar, light corn syrup, corn starch, and food coloring. It will be ready to use in a couple of days. (Must dry first.) I should save the emptied store-bought watercolor palettes that the kids have used up to have them make these.
Another Pinner said: This kept my 2 year busy for an entire hour and my 4 year old busy for 2 hours! YAY! Drop vinegar tinted with food coloring onto a pan filled with baking soda. Sheer minutes of colorful fizziness!!... Pretty sure we will be doing this soon! GENIUS!