This DIY Light Table is such a wonderful idea! Just think of all the amazing art projects you can do with something like this, not to mention the fun kids will have learning how to trace--which helps build solid drawing skills.
Another pinner says: Mess Free Finger Painting! What an awesome idea! Paint in a ziploc bag taped over a piece of paper. Of course we'll have to REALLY finger paint sometimes, too, since getting messy is half the fun.