Start by using Sculptey or Sculp-It. Something you can bake in your own oven. Shape your arrowhead, making sure to leave a hole in the top for the chain. Bake it according to the instructions and let it cool. Once cool, spray paint with your choice of color, and then give a clear coat. I added a glass bead to one of mine, by adding the bead and then baking it into the Sculpt-It.