Paint on aluminum foil: add a small amount of dish washing liquid to your paint mix. Not only will that make cleaning up easier but it also helps the paint to stick to the foil better and not flake off when it dries. Art for kids.
raised salt painting: create design with glue, cover glue with table salt. Touch watercolor brush on salt, without smearing and watch color be absorbed by salt. Let dry. This looks fantastic. So, inverted rock salt painting.