Carbine is partnering with PC Gamer to give players a chance to build one of WildStar's weapons. Actually, let me back up. You're not really building a weapon as much as you're voting for one of four pre-existing Carbine designs.
The first is an Esper multitool, the second is some sort of toaster, the third one is a beer cannon, and the fourth one is a "mystical pointy uprooted tombstone with a handle," according to producer Stephan Frost. You can see all the choices in the video after the cut.