Easy! You make a system that does it all for you. In an SXSW panel, Sieben and Armstrong spoke about the systemic development tool named Gearbuilder that they developed, going into detail about how they created the system to handle the creation of that many customized guns. It generates the guns based on one of 12 different manufacturers, giving each one a different grip, body, cylinder, barrel and accessories. Based on those, that same system determines how much damage the gun will deal. But what's surprising is, as impressive a figure as 16 million is, it's still only one gun. Shoot on through the break for more.