A fully articulated Portal Turret is brought to life by an Arduino and a raft of sensors as well as servo motors assembled in a 3D printed shell.

Valve’s 2007 puzzle platformer Portal and its 2011 sequel may be well over a decade old, but makers and embedded systems enthusiasts continue to recreate the quirky murderous robots from the franchise to this day. And Dutch video game developer Joran de Raaff’s version of the Portal Turret may be the best one yet. What’s more, you can even make this at home thanks to its painstakingly comprehensive documentation.

Secret Sauce: Clever Gearbox for Convincing Kinematics

Joran de Raaff’s take on the Aperture Science Sentry Turret may not fire live ammunition, but it nevertheless incorporates the game’s trademark IKEA-esque minimalist design and the deceptively cutesy voiceover designed to lure unsuspecting test subjects into its line of fire.

The project utilizes off-the-shelf components, such as the Arduino WeMos D1 Mini 3 Wi-Fi development board (some more ESP32 gaming projects) along with an ADXL 345 accelerometer and a PIR motion sensor, which allows the turret to go on a simulated murderous rampage upon detecting movement.

The Sentry Turret mimics gunfire by using a clever arrangement of servos, LED lights, and an onboard MP3 add-on board to recreate the recoil, muzzle flash, and witty one-liners. However, the sheer compactness and quality of the kinematics sells the illusion better than more complicated attempts in the past, such as Ytec 3D’s stab at the Portal Turret.

The secret to this turret’s top-notch kinematics comes not only from the painstaking programming effort, but also the brilliant gearbox design that greatly increases the inexpensive SG90 servos’ torque as well as movement speed. The result is significantly less wobbly and agile movement of the turret wings, without having to spend big bucks on powerful servos.

How Challenging Is This DIY Sentry Turret Project?

Painting and 3D printing the turret’s shell and motion system components are the most difficult parts of this DIY endeavor, whereas the code and schematics required to make the electronics work are a relatively straightforward affair. All thanks to the excellent documentation. The project also includes the source code. This should allow other makers to incorporate potentially interesting new features.

De Raaff seems to have an excellent grasp over the 3D printing process, as evidenced by how well the STL files have been optimized and oriented for FDM 3D printing—a luxury that’s exceedingly rare in such projects. The files come pre-arranged for the typical bed size common on most low-cost 3D printers, such as the Prusa Mini and Creality Ender-3. If you own the latter, you might want to check out our our Ender-3 upgrade guide.

We recommend sticking to this layout and following the official project instructions.

An Interactive Memento of Valve’s Glory Days

For a corporation that dominates the gaming landscape, Valve only made precious few games before figuring out that real money lies in video game distribution instead. However, the games it did make left a lasting impression and were consolidated as pop culture icons.

Nothing underscores this better than the fact that Portal fans continue to spend countless hours recreating the in-game automatons in real life. If you’re a fan of Cave Johnson’s work, you might want to give this one a go.