Empty toilet paper tubes are easily accessible and accumulate quickly with the help of school custodians and parents. Here are a few projects we did in my art class recently, using those tubes.
We cut each cardboard tube into 4 or 5 rings. Then we painted, arranged and hot glued them together to form several pieces of wall art. From a distance it looks like metal. I was more involved with this project since most of my students can't use a hot glue gun safely, but everyone kept busy with our collaborative projects and a few made their own ornaments and wreathes.
These owls took about 30 minutes to make. I offered googly eyes and feathers, but most students chose to use markers and construction paper, with charming results.
The ends of tubes can be dipped in paint and stamped on paper to create circles. If those ends are cut with slits or triangles and fanned out, flower or star shapes are created. Tubes can be folded into triangles or squares as well. Since the tubes were free, there's nothing to loose with a little experimenting. Stamping is a form of printmaking and pattern/repetition is a principle of design, so we're covering the art standards in a way that is fun.