Radio frequency identification (RFID) tags have broadly replaced traditional keys in hotels, places of employment, apartments, and single-family homes. RFID codes have the advantage because disabling and replacing them takes much less time and effort than changing locks and cutting new metal keys. But like keys, it’s easy to forget or misplace an RFID card or keychain fob. (I inevitably leave mine inside the hotel room at least once per stay.)

Now, a smart finger ring developed by a research team at the Fraunhofer Institute for Casting, Composite and Processing Technology IGCV in Germany might eliminate that problem. The 3D printed ring contains a tiny RFID chip capable of serving multiple functions. For example, the discreet ring could act as an electronic key, point-of-sale payment, and health insurance card, among other solutions.

The tamper-proof ring, printed using a process described as “powder bed-based additive manufacturing,” consists of multiple metal layers. A laser beam melts a fine metal powder, a little at a time, to build each layer. An RFID chip, inserted midway through the printing process by a robot, rests within an internal cavity. Printing the second half of the ring seals the chip inside seamlessly, making accessing or altering the chip virtually impossible.

The printing process offers precision control over the shape and size of the ring. Hopefully, that means future versions of the ring will be sleeker, less cumbersome, and more aesthetically pleasing than the bulky prototype. It’s safe to say few consumers wish to wear a ring that looks like a cement block stamped with the letters IGCV.

The chip inside the ring receives power from the RFID reader when scanned, so it requires no batteries. Beyond keys and other everyday uses, the ring potentially has applications in healthcare. These might include personal medical data, tracking individuals living in residential facilities for safety, and as a component of some types of remote patient monitoring.