Simply squirt paint into ziploc bags and make sure they are sealed shut (you can add tape if you're nervous about your kids opening them).

Adding two colors is an interesting way to experiment with color mixing. Older kids can practice writing their letters.

We also experimented with running various things over the paint - toy cars, a small pumpkin, and even Baba got in on the action! If you tape the bag to your table, kids can come by and play with it over and over!