It was while I was working on the piece when I realized I had missed something. There are supposed to be circular blue gems at several places on the outer border of each shoulder piece. But the papercraft base didn't allow for mounting them.
Several others who used Pepakura for props discussed how they would cover the outside with Bondo for a smooth finish. I decided to do the same, and also create flat areas (sockets?) for the gems.
Once the shoulders have been finished, I will be able to securely glue the gems into place.