Looking for a fun Rainbow themed activity to do with your kids? This Rainbow Foam Dough is soft, silky, and squishy - and best of all, it's easy to make. How to Make Shaving Cream Playdough Recipe - Easy Foam Dough. Your children will love to squish the shaving cream and cornstarch together to make a batch of foam playdough for an afternoon playdate, sensory activity, or just some messy play.