Muffin tin
Can of shaving cream
Spoon
Food coloring (variety of colors)

Squirt shaving cream dollops into each section of a muffin tin. Add a couple drops of food coloring to each section and mix together with a spoon. Place the tin where kids can reach it while in the bathtub. Let them dip their fingers, hands or sponges into the paints and create pictures on the walls and tub. When bath time is over, be sure to rinse away the paint.