Valve’s 2007 puzzle platformer Portal and its 2011 sequel may be over a decade old, but creators and embedded systems enthusiasts continue to recreate quirky murderous robots from the franchise today. And Dutch video game developer Joran de Raaf’s version of the Portal Turret may be its best yet. Plus, you can even make it at home because of its painstakingly comprehensive documentation.

Secret Sauce: Clever Gearbox to Explain Kinematics

Joran de Raf’s live ammunition on the Aperture Science Sentry turret may not fire, but it nonetheless includes the game’s trademark IKEA-esque minimalist design and deceptively catchy voiceover that allows unsuspecting test subjects to fire their line of fire. Designed to seduce.

The project uses off-the-shelf components, such as the Arduino WeMos D1 Mini 3 Wi-Fi development board (some more ESP32 gaming projects) with an ADXL 345 accelerometer and a PIR motion sensor, which allow the turret to move on a gives. Fake deadly stampede upon detection of movement.

The Sentry mimics bullets using a clever arrangement of servos, LED lights, and an onboard MP3 add-on board to recreate turret recoil, muzzle flash, and funny one-liners. However, the sheer compactness and quality of the kinematics sell the illusion better than more complex attempts in the past, such as the Ytec 3D stab at the portal turret.

The secret to this turret’s top-notch kinematics comes from not only the painstaking programming effort, but also the superb gearbox design that maximizes the torque as well as movement speed of the affordable SG90 servo. The result is significantly less wobbling and agile speed of the turret wings, without spending large sums 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, while the code and schematics required to make the electronics work is a relatively simple matter. Thanks all for the excellent documentation. The project also includes source code. That should allow other manufacturers to potentially incorporate interesting new features.

De Raf seems to have an excellent grasp on the 3D printing process, as evidenced by how well STL files are optimized and oriented for FDM 3D printing—a luxury that comes with such projects. is extremely rare. The lowest cost 3D printers like the Prusa Mini and Creality Ender 3 have pre-arranged files for normal bed sizes. If you own the latter, you’ll want to check out our Ender-3 upgrade guide.

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

An interactive memento from Valve’s glory days

For a corporation dominating the gaming landscape, Valve made only a few precious games before discovering that real money lay in video game distribution. However, the games it created made a lasting impression and were consolidated as icons of pop culture.

There’s nothing better than the fact that Portal fans keep spending countless hours recreating in-game automatons in real life. If you are a fan of Kev Johnson’s work, you will want to give this a try.

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