Make the vertebrae for the spine from the white clay. Mold them by hand into the proper shape and carve a hole through the center for the "nerves." When making vertebrae for the entire model, make them slightly smaller at the top and at the bottom to mimic a real spine. The holes should line up when they are stacked on each other. Make the back part large enough to thread the wire hanger through.
Shape the wire hanger into the standard shape of a spine. Shape the extra wire at the bottom into a circle, so the hanger can stand. Thread the vertebrae onto the wire hanger before they dry, leaving space in between each one. Cut any excess wire off with wire cutters.
Place the gray clay in the spaces between the white clay. The gray clay represents the connective tissue in between each vertebra. Ensure the hole through the center of the vertebrae is not obstructed. Allow the model to dry thoroughly.
Add the nerves. Use colored string, yarn or thread to illustrate the nerves that run through the spinal column. Cut the thread to the correct length, and glue to the top vertebrae in the back. Use the red clay to illustrate where muscles connect, if the project requires.
Label the parts of the spinal column as required by the science project. Use the toothpicks and attach small slips of paper with the appropriate label. Labels could include the correct name with a separate display to explain the function or interaction of that specific part.