Also adding duct tape as another preferred medium for kid creations. It turns out you can get duct tape in various colors and designs and goes well with cardboard, packing peanuts, and other similar things. My dd chose to spend the $75 she won at a spelling bee a couple of years ago to buy things at Home Depot of all places, and she got bricks, little tiles, screws, hinges, and many other similar things. We also have all sorts of rocks, marbles, sea shells, and small toys in a large tub full of colored sand for amazing pretend plays. What I found helped her creativity in art at least was to banish all coloring books from the house, so she can create her own vision of the world rather than coloring within the lines. She's not the best artist, but she is creative.