Nowadays, my nearly three-year-olds love to paint, and can usually be trusted not to slime the universe when they do. I've been finding that the more frequently they paint, the more they seem to enjoy and get out of it, with each day's session somehow building into the next.
With kids' activities, I've learned, there's a good reason why the classics are the classics: Simple pursuits like painting don't just stimulate the imagination; they provide satisfying tactile pleasures and an outlet for complex emotions that toddlers can't yet articulate. More narrowly channeled activities, like toys that can be played with in only one way, don't address the range of toddler needs and desires the way open-ended ones do.
Are the kids also learning about color and form and gesture when they paint? Sure -- but that's not the point of it, at least not in my book. When you try to load too much "learning" into an activity for small children, you risk robbing it of its magic. Far better, I think, to leave it freeform and let your kids make of it what they will. They will almost certainly surprise you.
Doing it yourself? You can buy a mountain of high-quality supplies for a fraction of the cost of preschool tuition (unless, of course, you live in some extraordinary place far, far from Brooklyn where preschool is actually affordable). This is not a place to skimp, in my book: It's a drag to feel like you're rationing paint when your kids are reveling in the sloppy satisfactions of excess. Try buying washable tempera (or washable glitter paint!) from an economical source like Discount School Supply. You might also want to invest in a big roll of butcher paper or a ream of 18" x 24" paper.
First Art: Art Experiences for Toddlers and Twos by MaryAnn F. Kohl
A must-have guide to art activities for the very young, with a great overview of why "it's the process, not the product" when doing art with small children.
The Color Kittens by Margaret Wise Brown
Brown (author of Goodnight Moon) is at her dreamiest and most psychedelic in this sweet, beautiful tale of two kittens and their quest to create the color green.
Mouse Paint by Ellen Stoll Walsh
Another color-mixing tale, featuring a trio of mice who explore color as they outsmart a cat.
The Crocodile's True Colors by Eva Montanari
Truth be told, I find this book to be irritatingly didactic, but I'm including it here because my twins love it. A group of African animals learn about various styles of art as each paints its own fearful portrait of a crocodile. Cool illustrations, and before you know it your two-year-old will (sigh) be talking about "futurism" and "expressionism."