When Nathan Seidle was gifted a locked safe with no combination from his wife, he did what any puzzlemaster—or, rather, what any engineer with a specific set of expertise in locks and robotics—would do: He built a robot to crack the safe. Seidle is the founder of SparkFun, an electronics manufacturer based in Denver, and this gift seemed like the perfect opportunity to put his professional knowledge to the test.

The process of building a safecracking robot involved a lot of coding and electronics, but it was the 3D printing, he said, that became the most important piece. Seidle estimated that it would take four months to have the robot test out different combinations, but with one major insight, he was able to shave off the bulk of this time: While taking a closer look at the combination dial indents, he realized that he could figure out the third digit of the combination by locating the skinniest indent. Thanks to this realization, he was soon able to trim down the number of possible combinations from a million to a thousand.

Watch the video from WIRED below to see Seidle's robot in action, which effectively whittled a four-month safecracking project down to an impressive 15-minute job.