My son created this gigantic Masterpiece last month at our old apartment. All of his toys were packed away so this provided a good hour of entertainment for him and he LOVED IT! I saw this Fun Window Painting idea in The Toddler Busy Book awhile back and decided to finally give it a try. All I did was mix dish soap in with his regular paints (I use Crayola) and just a dash of water. He even got in on the clean up of it as well! I figured it would be easier to just clean up right away before it dried, so I let him have clean-up wipes to wash away his artwork (I sprayed the patio door with water first). He had just as much fun cleaning up as he did painting it!