A while ago, at a playdate, one of the other mother's mentioned this idea. You fill an ice cube tray with water and put food coloring in some of the water and let your kid mix them up on with an eyedropper. I'd read about it before somewhere online, back before Moira was capable of sitting up, much less holding an eye dropper, but I thought she might be old enough now.
She loved the set up, picking which holes to put which color in, getting the towel and cookie sheet. Unfortunately, the dropper was a little hard for her to do, and even after she figured it out, she got bored pretty quickly.
I caught her mid tip. We will try again in a few months. Maybe that will give me enough time to find some of the florescent food coloring (printer's primarys!) so she has more exciting colors to mix. I should try to find the Montessori idea blogs I was reading when she was an infant again. This would probably be a better time for me to collect that information.