an unbroken half of a nut shell (walnuts work well)
clay (or hot glue, if an adult is doing that part)
a piece of paper
paint or markers
Put a small wad of clay inside your halved shell. (I put dabs of hot glue, and NatureMan inserted the toothpicks)
Draw a small sail and cut it out. Glue or tape onto toothpick (or you could just stick the sail right through the toothpick.)
Your boat is ready to sail! You can make several boats and have races-- they really do float. :) Enjoy!