If you’ve played the new Call of Duty: Modern Warfare 2 game online then you know how badass a sentry gun is, they can take out the entire enemy team all by themselves. Well the folks over at Weapons Grade have put together this DIY to build a completely automatic and autonomous sentry gun. Its seems straight out of the Terminator but it’s actually quite doable. The instructions on everything from the firing mechanism to the open source control software for the sentry are all available online at the sit below. A video below shows the sentry in action, minus a gun attached to it. I’d totally build on, and attach a Nerf dart-shooting gattling gun to it.