Mould the modeling clay into a ball measuring 0.2 inches in diameter to make Mercury.
Wrap apiece of string or thread around the sphere and make a pen mark at the point it makes contact with itself. Measure the distance from the start of the string to the mark with a ruler or measuring tape, then divide this number by 3.142 with a calculator. This will show you the diameter.
Paint Mercury Brown
Form a ball 0.47 inches in diameter with modeling clay to create the plant Venus. Paint this planet orange.
Create a sphere out of modeling clay that is 0.51 inches in diameter to create Earth. This planet should be painted blue with large green patches.
Mould a 0.3 inch diameter sphere out of modeling clay to create Mars, and paint it red.
Form a ball measuring 5.6 inches in diameter from the modeling clay to create Jupiter. Paint this planet grey with a few white and brown lines running through horizontally. Don't make these too neat.
Shape a sphere from modeling clay 4.8 inches in diameter to make Saturn. Paint Saturn yellow with a few thin and faint brown lines running horizontally.
Create a ball 2.01 inches in diameter from modeling clay to make the planet Uranus. This should be painted a light blue.
Form the modeling clay into a sphere that is 1.97 inches in diameter to make Neptune. Paint this planet blue.
Push the thin end of a chopstick through the center of each planet and make a base out of modeling clay for the other end.
Paint the plank of wood black.
Allow all of the paint to dry.
Draw a faint line with pencil straight through the center of the wood.
Glue Mercury two inches along this line. Venus should be glued four inches along the line.
Stick down Earth six inches down the line and then Mars nine inches along the line.
Glue each of the planters 8 inches apart from this point in this order: Jupiter, Saturn, Uranus and Neptune. This is no longer in scale, because if it was Neptune would be more than 400 inches along the line.
Label distances. Place a card next to the base of each planet stating how the distance from the Sun. These distances are: 35,977 miles for Mercury; 67,232 miles for Venus; 93,205 miles for Earth; 141,672 miles for Mars; 483,613 miles for Jupiter; 886,696 miles for Saturn; 1,783,335 for Uranus; and 2,794,306 miles Neptune.