Things you will need:
Two shirts of contrasting color (one should be long sleeved)
Brass or silver buttons.
Scissors, thread, needle, etc.
Step 1: Making the Breast Plate
Take some chalk and trace an breast plate pattern to the front of the shirt.
Take a piece of newspaper and trace half of your pattern onto it. Fold over and cut out.
Pin to the other piece of fabric or old shirt- preferably a good contrasting color. Pin down the pattern and cut out, allowing a half inch seem allowance.
Pin a hem all around the garment and sew the hem.
Once you breast plate is complete, pin down and sew to the first shirt.
Keep the right side top (it will be on your left when it is worn) portion unsewn so you have enough room to get your head comfortably through the collar.
Step 2: Embellishing with buttons
Then take some extra fabric, same as the breast plate, and cut out two arrow shaped like pieces (see pictures) each one is going to about two to three inches in length and your going to sew all around the edges leaving the bottom open. Turn them inside out, place them on top of the shoulders of your shirt and sew them on. Then, exhaustingly, sew all the buttons on by hand. Make sure to leave the button on the top right corner off of your garment. Sew that last button onto your shirt directly, underneath where you'd like it to go on your breast plate and create a button home for it. And your done!