It's soooo satisfying to take something useless and repurpose it by resurrecting it, renewing it, reviving it, redeeming it… O.K. I've gotten a bit carried away here, but you get the gist -- the feeling of renewal is guilt free.
Actually I got the idea of combining white house paint and sand when studying cave art with my 7th graders. Ok, so the tight budget and desperation for materials had something to do with it too leaving me with donated sheetrock and house paint. We went out to the playground, gathered sand, sifted it, mixed it with the paint as thick as Cream of Wheat, spread it on the sheet rock like frosting on a cake, and while it was still wet carved a cave animal into it. The next day we painted it letting the darker colors settled into the incised areas defining our primitive beast. Other classes took the idea to a whole new level of recycle and guiltlessness when they imbedded junk into the wet paint/sand. ( Maybe it should be called "p a n d" which is a word I could use in my current scrabble game. ) Anyway they did end up using up all my metallic paints when they highlighted the surface with golds and copper.