Called Spinel, the material is made in a lab from synthetic powder. Under the right conditions, it can be shaped into strong, transparent sheets. The NRL has worked with the material for decades. Earlier production strategies used crucibles and high heat, which left behind imperfections that made the crystalline glass murky. To reliably produce clear material, NRL used a hot press under a vacuum. An added bonus to this method is that it allows the spinel to be pressed into shapes--for example, a dome for a new camera turret or a sloping panel that's flush with a wing.