I thought it would be great if the boys had a solar system model that they could build again and again with their own hands. We covered the inside of a large cardboard box with black construction paper. Me Too cut out the sun and glued it in the corner. I had a tube of cheap plastic planets from the craft store. They each have a length of fishing line tied to the top. Instead of adhering them to the box permanently I provided the boys with a container full of poster putty. They use the poster putty to stick the fishing line to the top of the box. That way they can create and recreate the solar system again and again.