"Cover a light bulb with a doily and spray paint it. The light will shine the pattern onto the walls." I don't know how I feel about flammable spray paint on a hot lightbulb. Maybe spray paint them silver and use them as non-light decoration?
Like shipping pallets, wooden cable spools are another item that is usually found for free on Craigslist. Since cable spools are limited by their shape there are fewer repurposing options, but they make a great coffee table bookcase.