Lorna, my daughter-in-law, and I thought it would be fun to "help" Jack make presents too. Handprints on paper came to mind but have you ever tried to get a 13 month old to make 11 good handprints? Judy and I tried that with Elanor one year and the poor kid was very unhappy. Not what we were after.
Lorna and I decided that "art" would be better than handprints. We stripped Jack down to his diaper. I put down drop cloths and we all wore our painting clothes. I got non-toxic washable Crayola paint that did, indeed, wash off when we were done. I used good paper in the hopes that these pieces will age well. Elanor helped - and at the end she got paint on her feet and made some really nice footprints!
We were able to cut out some surprisingly nice "paintings"! Steve shot movies. Here's a short segment showing the young artist at work... you'll notice that he's more interested in the snack than painting until we made that go away to the kitchen.