1. Decide how many shells to put on necklace. Shape Model Magic into shells with fingers, on the back of a teaspoon, or cut out shell shapes with a cookie cutter.
2. Use a straw to poke a hole into the top of each shell. Press designs into the shell with textured objects such as fork tines or sea shells.
3. Measure out yarn for the necklace. Cut it with scissors. Thread shells, tying each one separately. Allow necklace to dry overnight.
4. Attach the ends of the necklace with tape to wear.