When making these I highly recommend using white card stock for the fin and tail. I trace the shapes on card stock and have the students cut them out. If a student is done early you can have them decorate the nose and fin. I try to get students to make a compass rose on their plates (they learned how to in Social Studies so this is a great tie in).
Check your science kits (across grade levels) for the modeling clay but you can purchase from Walmart (approx. $4).