A Paintball Turret Controlled Via Xbox Controller

November 4, 2025 by Lewin Day 7 Comments

Video games, movies, and modern militaries are all full of robotic gun turrets that allow for remotely-controlled carnage. [Paul Junkin] decided to build his own, albeit in a less-destructive paint-hurling fashion.

The turret sits upon a lazy susan bearing mounted atop a aluminium extrusion frame. A large gear is mounted to the bearing allowing the turret to pan when driven by a stepper motor. A pair of pillow block bearings hold a horizontal shaft which mounts the two paint markers, which again is controlled by another stepper motor to move in the tilt axis. An ESP32 microcontroller is responsible for running the show, panning and tilting the platform by commanding the large stepper motors. Firing the paintball markers is achieved with solenoids mounted to the triggers, which cycle fast enough to make the semi-auto markers fire in a way that almost feels like full-auto. Commanding the turret is via an Xbox One controller; communicating with the ESP32 over Bluetooth using the BluePad32 library.

It’s worth noting you shouldn’t shoot paintballs at unsuspecting individuals, since they can do extreme amounts of damage to those not wearing the proper protection. We’ve featured a great many other sentry guns over the years, too, like this impressive Portal-themed build. Video after the break.

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Robot Nerf Alarm Blasts You Awake With Foam

January 21, 2022 by Lewin Day 11 Comments

The sentry gun targets [Vinnie] with blasts of foam as he runs through the bedroom to the sounds of Your New Morning Alarm by [Marc Rebillet].

Waking up is hard; sometimes you need more than a little chiming alarm to get you out of bed. When [Vinnie Satriale] started unconsciously switching his alarms off, he went all out, deciding to build a Nerf sentry blaster to wake him up instead.

A Nerf Rival Nemesis MXVII-10K flywheel blaster is the core of the build, with a 100-round capacity of soft foam balls. Stepper motors are used to control a pan and tilt system to aim the blaster. It’s moved under instruction from a Raspberry Pi that uses machine vision algorithms running on a Coral USB accelerator to track targets in the bedroom. A relay board is then used to activate the blaster’s firing action, blasting any targets until they wake up.

[Vinnie] had plenty of fun during build, also showing the sentry gun off to his coworkers in the office. It’s a hard sentry to dodge, with the machine vision algorithm using a full-body tracking model, so merely covering one’s face won’t be enough to get away.

We’ve seen all kinds of sentry guns over the years, from those firing rubber bands to others spraying jets of water. Video after the break.

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A Nerf Ball Turret Complete With FPV

July 23, 2021 by Lewin Day 2 Comments

Sentry turrets have long been a feature of science fiction films and video games. These days, there’s nothing stopping you from building your own. [otjones99] has done just that, with his FPV Nerf Ball launcher.

The system works on the basic principle of launching soft foam balls via a pair of counter-rotating wheels. It’s a remarkably simple way of electrically launching projectiles without a lot of fuss and mucking around, and it works well here. A blower fan is used to gently roll ammunition towards the launcher wheels as required. There’s a hopper-style clip which uses a servo to drop one ball at a time into the launching tube.

An Arduino Uno is responsible for slewing the turret, and handling the firing process. A joystick is fitted with an NRF24L01 radio module to send signals to the Arduino to aim the turret, while an FPV camera mounted on the turret allows the user to remotely see what the turret is aiming at. With a simple pull of the joystick’s trigger, the turret opens fire.

It’s a fun build, and one that shouldn’t do too much damage to anything given the soft pliable nature of the Nerf ammunition. Of course, if you don’t want to aim your turret yourself, you can always go ahead and build yourself an automated sentry gun. Video after the break.

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Sentry Water Gun Relies On LIDAR

June 24, 2020 by Lewin Day 5 Comments

As we head into summer, Super Soakers and their ilk become de rigeur ways to cool off in the heat. Not content with chasing targets himself, [Marcel] instead built a sentry water gun to do his bidding.

The build is one that leverages typical 3D printer components to get the job done. A Minitronics 2.0 board is used to run the show, packing a 40 MHz SAMD21 microcontroller for plenty of grunt. It’s Arduino compatible too, making it easy to program. It’s combined with NEMA17 and NEMA23 steppers and an external driver board to slew the gun towards a target. Target detection is via a RPLIDAR A1, which detects the range of nearby objects. This data is used to calculate the pan angle and tilt required to hit the target with a stream of water, fired by a relay-controlled solenoid.

It’s a fun build that does a good job of soaking those playing by the pool. [Marcel] aims to do further work to improve performance by reducing backlash and increasing slew speed. Sentry guns are a forever popular build around these parts. Video after the break.

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Auto-Tracking Sentry Gun Gives Deer A Super Soaking

January 26, 2018 by Dan Maloney 29 Comments

Things rarely go well when humans mix with wildlife. The problems are exacerbated in the suburbs, where bears dine on bird feeders and garbage cans, raccoons take up residence in attics, and coyotes make off with the family cat. And in the suburbs, nuisance wildlife can be an intractable problem because the options for dealing with it are so limited.

Not to be dissuaded in the battle to protect his roses, [dlf.myyta] built this motion-activated sentry gun to apply some watery aversion therapy to marauding deer. Shown in action below against a bipedal co-conspirator, the sentry gun has pretty much what you’d expect under the hood — Raspberry Pi, NoIR camera, a servo for aiming and a solenoid valve to control the water. OpenCV takes care of locating the intruders and swiveling the nozzle to center mass; since the deer are somewhat constrained by a fence, there’s no need to control the nozzle’s elevation. Everything is housed nicely in a plastic ammo can for portability and waterproofing. Any target that stands still for more than three seconds gets a hosing; we assume this is effective, but alas, no snuff films were provided.

We’re not sure if [dlf.myyta]’s code can discern friend from foe, and in this litigious world, hosing the neighbor’s kid could be a catastrophe. Perhaps version 2.0 can include image recognition for target verification.

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A Touchscreen From 1982, That Could Kill With A Single Finger Press

April 17, 2017 by Jack Laidlaw 73 Comments

Over the pond here in the UK we used to have a TV show called Tomorrow’s World, It was on once a week showing all the tech we would have been using in 10 years time (or so they said). In 1982 they ran with a story about a touch screen computer. Perhaps not what you would recognize today as a touchscreen but given the date and limited technology someone had come up with a novel idea for a touchscreen that worked sort of.

It was a normal CRT screen but around the edges where photodiodes pointing inwards as if to make an invisible infrared touch interface just half an inch in front of the screen. Quite impressive technology giving the times. As they go through the video showing us how it works a more sinister use of this new-fangled touch screen computer rears its ugly head, They turned it into a pretty cool remote-controlled gun turret complete with a motorized horizontal and vertical axis upon which an air pistol was placed along with a camera. You could see an image back from the camera on the screen, move the gun around to aim the weapon, then with a single finger press on the screen, your target has been hit.

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Taking Killer Robots Seriously

June 27, 2016 by Elliot Williams 61 Comments

Killer robots are a mainstay of science fiction. But unlike teleportation and flying cars, they are something that we are likely to see within our lifetime. The only thing that’s stopping countries like the USA, South Korea, the UK, or France from deploying autonomous killing machine in the very near term is that they’re likely to be illegal under current international humanitarian law (IHL) — the rules of war.

But if you just sighed in relief that the fate of humanity is safe, think again. The reason that autonomous killing machines are illegal is essentially a technicality, and worse, it’s a technicality that’s based on the current state of technology. The short version of the story, as it stands right now, is that the only thing making autonomous robotic killing weapons illegal is that it’s difficult for a robot to tell a friend from an enemy. When technology catches up with human judgement, all bets are off.

Think I’m insane? The United Nations Office at Geneva (UNOG), the folks who bring you the rules of warfare, started up a working group on killer robots three years ago, and the report from their 2016 meeting just came out. Now’s as good a time as any to start taking killer robots seriously.

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