The Exploratorium in San Francisco has offered up this rather fun and interesting activity which gives interested parties the information to build their own scale model of the solar system. Visitors can start by filling in the diameter of the Sun (which sets up the scale of their model), and the program will give them the necessary dimensions for their scale model. The site also has a list of materials that will be required, and they include a tape measure and a toilet paper roll. The activity is quite fun, and it can be enjoyed by budding astronomers of all ages.