What you'll need:
Box of cornstarch
Bottle of shaving cream
This stuff was so much fun! All you have to do is put a box of cornstarch into a bowl with a bottle of shaving cream (cream, not gel) and go to town!
I've heard of other ways to do this same sort of dough but this was the easiest and we had both things in the house.
Evie had a great time molding the dough how she wanted, she built a snowman, made snowballs, and I gave her small toys and molds and she played for an hour with this. So much fun and so easy!