This is a bit messy, but super fun.
Squirt shaving cream on the table or counter and then just let them play 
. For younger ones it’s a good way to practice writing letters, or drawing shapes or faces, etc. When I taught first grade we often did this favorite Friday activity to practice spelling words just before taking the test. (Plus, the desks got nice and clean!)
I have a piece of clear vinyl on our dining room table to protect it, but if you’re worried about the mess you could always squirt the cream on the shower walls and let them play in the bathtub.
[...] Bath Art Supplies: Let them create a mural on the wall with bath crayons, body paint, etc. OR, try shaving cream. [...]