Suggested materials needed to make a model solar system include Styrofoam balls, paint, string, dowels and a reference book to help make the model as accurate as possible. The materials used will depend on whether the planets will be suspended from above, or held in place from below.
A model with suspended planets is more animated. Styrofoam balls work well because they are light, come in many sizes and can be painted easily. One popular option is to take a wire coat hangar and shape it into a circle.
Using string, fashion a harness to suspend the mobile by tying equally measured pieces to the edge of the circle and attaching them to a hook that will hang from the ceiling. Using another piece of string, suspend the Sun from the hook so it sits in the middle of the circle.
Paint the planets, and label them if needed, then hang them from the edge of the circle using different lengths of string. Put Mercury on the shortest string, then Mars, then Earth and so on. By hanging each planet in order and using longer and longer bits of string, the model will reflect the order of the planets, but not the distances from the Sun. This information can be placed on the labels.
A solar system using the dowels is mounted on a base, usually a piece of plywood. By placing the Sun in the middle and the planets at increasing distances from it, this model shows the spatial relationships between the planets.