Start with muffin tin, food coloring and foam shave cream:
Spray some foam in each tin:
Drop some food coloring – mix your primary colors to get more colors:
We have a floating mat in the tub which I set this on, but you could rest it or hold it:
Voilah, painting fun!
This washes off with no problem and my boys had a blast! Perfect for all that shaving cream or food coloring you have left over. Also, make sure you use shave foam and not gel – cheaper the better. (Even Olivia in there!)