Finger Paint
I found a recipe for non-toxic "finger paint" on Saturday (cook water, cornstarch, salt, and sugar on stove top. Then add food coloring). It turned out more like finger paste than paint, but Caleb and I still managed to have fun while Todd was on campus trying to finish a lab.
Step one: Make paints/pastes
Step two: Dressing appropriately
Step three: play with gross stuff
Step four: eat gross stuff
Step five: wait for Mom to clean up the mess