If you know messy children with artistic inclinations, you're in luck: Our Rainy Dayz Gel Crayons write on—and, most importantly, wipe off of—windows, mirrors, and other smooth surfaces. We suggest you test the rainbow set of twelve before use and supply little artists with a sketchbook, too: The handy tools color particularly bright on paper, and when combined with water, bleed gently to create a watercolor effect. The non-toxic markers for ages 3+ come in a portable case.