Paper Mache
Construct your solar system using found or recycled materials. Instead of purchasing Styrofoam balls, you can create your own paper mache balls using balloons. Just blow up various-sized balloons to make planets. Create a glue solution using three parts white glue to one part water. Tear long strips of newspaper or other recyclable paper. Dip the strips in the glue solution and apply onto the balloon. Continue applying paper until balloon is covered. Let dry. Paint the planets and hang from a mobile.
Food
Construct a fun and delicious solar system using biodegradable produce that you can eat after use. Use a large pomelo to use as the sun. To make the earth, use a green apple. You can either cut out an ocean from paper and tape to the apple or paint it with non-toxic edible paint, made from cornstarch, sugar, water and food coloring. Other fruits you can include: red apple (Mars), pomegranate (Venus). cantaloupe (Jupiter), apricot (Mercury), honeydew (Neptune), white peach, (Uranus), orange (Saturn). Wrap liquorice around the planets to make rings.
CDs
Transform your old CDs into a clever planet mobile. Use a strong pair of scissors to cut the CDs into smaller circles for the various sizes of planets. Paint designs or labels directly on the surface or cover with paper cut outs, stickers or glitter. Cut yarn pieces. String the yarn through the discs and tie them to a wire hanger to make a hanging mobile.
Sports Balls
Give new life to your old sports equipment by including them in your eco-friendly solar system model. For the project, you'll need different-sized round balls for each planet. Tennis balls, golf balls, baseballs, racquet balls will all work. Color or label the balls to their corresponding planets. You can either glue the balls to a frame or attach them to yarn to hang on a mobile. Create a simple mobile base, using a piece of heavy cardboard, such as an old pizza box. You can round the edges and punch holes around the perimeter. Insert the yarn through the holes and tie ends to secure.