One of my favorite sensory activities to do with littles is letting them play with shaving cream. I buy super cheap cream at the dollar store and then squirt it onto the table. He spreads it around, smooshes it, and can even write letters or draw pictures in it. It's such a great tactile experience!
Quartus was excited to discover that "I can shape it!" He tried piling it up like a sandcastle and was just tickled when he saw that the way it collected around his hand created what he thought looked like a robot's "gun hand." He also found what looked like a mouse and a chicken.
Sometimes I add a few drops of food coloring and let him mix that in for another fun element. It's also very entertaining for me to watch him try to wipe cream off of a place that he doesn't want it but actually end up making a bigger mess!
Cleanup is super easy. When the kid is done, he gets escorted to the bathroom with his hands in the air. The shaving cream comes off easily with water. Then I scoop up the majority of the mess on the table with paper towels and then it gets wiped down with water, too.