Not only can the Nerf Vulcan Sentry automatically shoot darts of foamy death at your opponents while you sit back and laugh at their misery -- you can also set it to discern potential targets based on shirt patterns, meaning it will shoot only those you've labeled as your enemies (like, say, anyone wearing a Tapout T-shirt).
We're pretty sure that's exactly how the military version works, too.
You can read the step-by-step instructions on how to make one here, but if this one's too complicated/intense for you, Liv has also posted tutorials on how to mod several other Nerf gun models to shoot faster, harder, and generally kick more ass. She even designed an in-barrel meter that can track how fast the darts are shot out, presumably in order to calibrate the exact amount of force necessary to kill a grown man with a small foam projectile.
She's either the biggest Nerf fan ever or the world's least intimidating super villain.