Native American breastplates were originally worn as protection while hunting or during battle. In the desert climate of the American Southwest, they were often worn over a bare chest in the hot summers and over a shirt in the cooler winters. The original breast plates were made with bone and tied together with sinew strips usually taken from a deer or buffalo, and were often created by a tribal "specialist." You can make your own "costume" breastplate from ordinary materials.
Cut 50 of the straws in half. Cut the additional 50 straws into four equal pieces. Sponge a little dark acrylic paint at one end of each straw to give them the appearance of bone.
Loop the yarn through a straw and place a bead on the outer end. Loop another piece of yarn through the same straw piece and a second straw piece, again placing a bead on the outer end. Continue until you have a strip of 25 straw halves. Start a second strip for the other 25 straw halves. These are the two outer strips.
Use the above method to string together the quarter-length straw pieces to form two longer strips. These will be the inner strips of the breastplate.
Tie the two long narrow strips together then tie a short, wide strip on each end.
Add feathers or frayed string to the bottom of the breastplate. Tie a longer string to the top of the breastplate and tie the whole piece loosely around the neck.