Listen, we’d all love to own some singsongy turrets from Portal. This isn’t in question. However, we live in the real world, and the best we can do is a do-it-yourself, autonomous Nerf sentry gun that can recognize a specific target and grant it safe passage. If it makes you feel better, you can paint it white and play the turret opera on loop wherever you need some sentry gun protection.This black sentry gun started out as a bright orange-and-yellow Nerf Vulcan — an automatic foam dart gun that makes you realize toy tech has come a long way since the foam disc pistol. The Vulcan isn’t created autonomous, so Instructables user BrittLiv played Nerf-God and began work. Like any good turret, the unit automatically aims and fires at targets, but won’t fire at a predesignated target — in this case, anyone wearing a shirt with an Instructables logo.BrittLiv built the rig using existing designs for a paintball sentry gun, but modified it using the Vulcan. The Nerf gun’s spring was too slow, so she replaced it with one that increased the firing speed by about 50%. The gun moves around thanks to some servos, as well as an Arduino Uno controller. If you like to do your own dirty work, though, the gun is controllable with a joystick, gamepad, or mouse.In the above demonstration, the turret follows her around rather quickly, but if someone was running at full speed without doubling back, the turret likely wouldn’t be able to hit its target. The gun certainly shoots fast enough, at least.Though BrittLiv built the gun in only 11 steps, the project does appear to require more know-how than just the ability to follow steps without having much build intuition. However, if you learn by doing, then at least learn in a safe environment with a supervisor.