An atom is one of the most basic units of matter in the known universe. Of course, you'll learn that far smaller components exist as you move forward through the physical sciences, but for the purposes of basic chemistry and physics, the atom--along with the protons and neutrons that make up its nucleus, and the electrons that orbit it like planets around the sun--is as basic as you'll need to get. If you want to make a model of a neon atom, you should keep in mind that it has 10 electrons.
Spray paint your foam balls to differentiate what they represent. Separate them into three groups: the large foam ball, two of the small ones, and the remaining eight. Lay each group on a different piece of newspaper (to protect the surface) and spray each group a different color, making sure your room is well ventilated. The large ball represents the atom's central nucleus, while the first two small balls represent its inner two electrons. The other eight balls represent its outer, or valance, electrons. Allow the balls at least two hours to dry before handling them.
Label the nucleus (large foam ball) using a black, permanent marker. Write neon's symbol "Ne" on it, as well as "P: 10" and "N: 10" to indicate the respective numbers of protons and neutrons.
Snip a piece of craft wire long enough to form a ring outside the nucleus and thread it through the two designated inner electrons (small foam balls). Attach each of the electrons to the nucleus using a short piece of a cooking skewer inserted into both the electron and the nucleus.
String together the outer shell as you did the inner one and attach it to the nucleus as well, keeping in mind that you need only attach two to four of the electrons directly to the nucleus--and that the piece of skewer you use should be at least twice as long as the one you used for the inner shell.