A 3D printing video from National Geographic went viral on the interwebs last week and quickly generated some controversy among 3D printing enthusiasts.
In the video, physicist David Kaplan visited ZCorp HQ to "find out whether they can print a crescent wrench". Kaplan was shown a selection of amazing items printed on ZCorp devices, including multicolored objects with moving parts, as well as the standard explanation of how 3D printing actually works.
Then the interesting part occurred. Kaplan's substantial wrench was put under a hand scanner, capable of capturing highly detailed 3D information. It then appeared as if this captured data was then converted into a proper 3D model, "creating an image that will be sent to the printer".
Then, just like you'd see on a TV cooking show, the printer was opened and a printed wrench was extracted from the powder. While the wrench was demonstrated to be strong enough for actual use, questions immediately arose.
We're wondering how a hand scanner can discern moving parts, such as are found in a crescent wrench? We know of no technology that could do such a thing, particularly when the video showed no part motion during the scan. Viewers were left with the impression that you could simply wave your scanner at anything and hope to replicate it immediately - including hidden internal moving parts, and by extension even electronics!
That's just not possible. This was noticed and challenged by several sources, including on Jon Udell's blog, where a discussion erupted (link below).
Scan captures are usually nowhere near printable state, and always require at least minor if not major editing and conversion before printing can be attempted. Worse, a given object's geometry might not be printable on a given 3D printer - the right 3D print technology must match the object.
Providing general awareness of 3D printing is a good thing, but leading people to unrealistic expectations is not helpful. We fear that a growing abundance of such memes will eventually cause a backlash towards 3D printing, as folks will soon discover that you can't simply replicate just anything.
Correction: you can't replicate just anything - yet.