Chocolate Dirt is a really fun sensory toy. It's mostly baking soda and some cocoa powder, enough vegetable oil to give it a moist sand texture, and a sprinkle of glitter. It smells good, feels good and tastes terrible! We've had that same tub sitting outside with the lid since early fall and it's still good. As long as water doesn't get in it it should last even longer.
These are planets he drew in the dirt.