Adventures of a Middle Sister: DIY Tie-Dye Swimsuit Cover-up. Plain white oversized T-shirt, tie-dye kit, scissors, needle & thread. Could use a T-shirt that's already colorful and skip the tie-dye step.
"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?