Engineer Builds Real-Life Version of Rocky, the Conversational Alien Robot From Project Hail Mary

Project Hail Mary introduced fans to an unforgettable alien named Rocky. Many who finished the book wanted more time with the character and his quirky way of speaking. One maker decided to satisfy that craving by constructing a physical robot that captures the essence of Rocky in every joint and word.

The engineer behind Leviathan Engineering worked tirelessly on this project for months, bringing Rocky to life. He began with digital models of the character purchased from 3D Totems, a store that does an excellent job of creating 3D models that are precisely perfect. Next, software programs such as Fusion 360 and Tinkercad were used to ensure that the parts were not only printable, but also strong enough to endure some hard treatment.

Months later, the printed components came together to create the body of a four-legged monster with arms that appear to lunge out at you in all the right ways. Ten metal-geared servos provide the driving force behind the movements, cleverly placed to allow the robot’s expressiveness to show. The shoulders each receive an additional servo for arm swings, while the knees of the legs receive one each for low crouches. Movement, gestures, and body language pull the alien’s exuberant personality straight out of the novel. He even gets to offer you a full fist bump, or make a wild arm gesture, just like in the novel.

The robot is powered by a Raspberry Pi 5 that is connected to a circuit board known as the PCA9685 HAT, which operates the servos and controls all of their motions. Power comes from an external supply because the motors draw plenty of current during lively movements. Software brings everything to life. It has speech recognition integrated with Vosk, so you can tell it what to do without experiencing internet lag. Then there’s Piper for the robot’s voice, which has that really unique, staccato talking style that we all love about Rocky. For talks, however, it uses Google’s Gemini model, which essentially determines what the robot says and even what gestures to make based on the situation.

The maker wrote all the code using assistance from Claude through its command line interface. No fixed animation scripts exist. Instead the language model chooses movements based on context through a process called tool calling. Ask for a fist bump and the arm extends while the robot says something like “fist bump yes much happy.”

Of course, like any good maker project, this one had some challenges along the way. The engineer experimented with pulleys and linear actuators before settling on servos since they provided him more control over the entire mess. To ensure that printed joints did not break under any force, he had to do some trial and error before getting it perfect. Then there was the enjoyable task of putting things together, a little hot glue here and little super glue there to keep everything from falling apart. Wires route neatly inside the body thanks to extension cables. The final assembly stands about the size of a small tabletop model yet moves with enough grace to feel like a living creature from the pages of the novel.
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