A 3D-Printed, PIN-Protected Door Lock Won't Protect Your Home But it Sure Looks Cool

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3D printers may have failed as a home appliance, but researchers at the Hasso-Plattner-Institut aren’t ready to give up on them just yet. Last year they successfully 3D-printed a working door handle without any moving parts, and this year they’re following it up with a 3D-printed, PIN-protected door lock.

The 3D-printed door handle worked by taking advantage of 3D-printing’s ability to churn out incredibly complex, although completely static, objects. By creating the door handle’s structure as a grid of cells that could collapse in pre-defined directions when pressure was applied, turning the plastic door handle resulted in the latch retracting, without requiring a single moving part to be assembled once printing was complete.


Building a working PIN-protected lock using just a 3D printer was a little more complicated, but given the world’s first computers were purely mechanical creations, it turns out you don’t need electronics and circuits to secure a door.

The secret to the 3D-printed lock’s functionality is a series of plastic bistable springs which can be resting in one of two different positions—as opposed to a metal coiled spring that always wants to expand. Pressing the correct sequence of buttons on the outside of the lock triggers specific springs inside it, which results in a larger chain reaction occurring when someone tries to unlock the door—if they’ve entered the correct PIN.


Like with last year’s 3D-printed door handle, as clever as this locking mechanism is, no one is going to want to secure their homes with a plastic lock that can be shattered with little more than a gentle tug on the door handle. This research, however, demonstrates that while the average home doesn’t need a 3D printer, the technology still has fantastic potential when it comes to manufacturing more than just trinkets.

Through clever engineering, entire machines can be created without the need for assembly after the printer has completed its work. And one day, 3D printers might just might be a good enough substitute for Star Trek’s long-awaited replicators.