Part 3: Prepare the Fins:

Use plain old cheap blue foam closed-cell camping mat for the fins. If you like to throw the javelins a long distance and want the best spin and stability use the long pattern, but if you plan mostly on thrusting and throwing shorter distances use the short pattern. You also can certainly use no fins at all. You will need a pair. Lay the patterns on the foam mat, draw around them and then cut them out with heavy scissors or a hot wire foam cutter available at craft or floral stores.

Choose your favorite color of duct tape and cover the fins with a single layer of duct tape. Make sure all foam is covered. Snip the tape to fit.