lol I saw your tweet and wasn't sure if you were really being serious till now. A woman who is wearing armor is likely to be physically active, meaning those melons are going to be bouncing in a lot of different directions. "Lumps" could be considered 'cupholders' in the sense that they secure them in place; however, that exposes the sternum as you've said, which is just poor design. Therefore, a hybrid of the lump mechanism together with a properly armored breastplate would be the most efficient method. Perhaps lumps that are reinforced by a centered vertical plate protecting the inversion of the chest. Whatever the case, as long as it's designed to be practical rather than presentable.