I primed all of the armor pieces front and back with flat black Krylon Fusion spray paint and finished with Krylon Fusion Hammered Metal spray paint, following the directions on the can to ensure best adhesion.
Once the paint had cured, I assembled the whole thing using pop rivets in the rivet holes I had drilled earlier, and some more hot glue to “weld” the edges of the collar pieces in place. The paint got a little bit chipped from the riveting process, but this was easily touched up with a bit more spray paint along with the hot glue on the collar.
I had planned to hold the open seams of the arm pieces together with Sticky-back Velcro, but as it turned out, the adhesive wasn’t strong enough. I wound up just riveting the upper arms together permanently, but the lower arms fit too closely for this. I sewed the hook side of some Velcro to a leather strip the length of the lower arm and twice as wide as the Velcro. I riveted the leather flap inside the lower arm with the hooks facing out, and riveted the loop side of the Velcro inside the lower arm on the other side of the seam. A little more paint for touchup, and the armor was finished.