3D printing doesn’t per se pose a threat to privacy (although we have heard [unsubstantiated] rumours of printers passing information about prints back to manufacturers). The issue we have raised is in the use of watermarks to reveal information about the activities of users. For example, a watermark embedded onto a 3D printed object could be tracked and traced through photographs online, e.g. through google image search. If this were, say, a piece of jewellery, it might be a way to track the movements of an individual; likewise, some 3DP implants could be traced through the use of x ray equipment. The files themselves could also be searched for online. The possibilities are, ultimately, endless.
Similar technologies can be employed by the IoT, indeed, there is some overlap. However, the interesting thing about 3D watermarks is that they could be on an analogue physical object, and they can be different for every single print. In effect, it could allow for a blockchain or Google search for physical objects – imagine that! As the IoT becomes more predominant, then these devices could recognise 3DP watermarks, in effect bringing together the 3DP analogue world and the digital world. If, as one would expect, 3DP becomes mainstream in the future, then we can see that the use of 3DP watermarks in conjunction with IoT could become rather common and a critical component in our everyday lives.