Here's a summary for those of you who missed it: last week, Ulrich Schwanitz figured out how to print the "impossible" Penrose Triangle," a well-known optical illusion. He released a video of the shape and challenged others to see how it might have been done. 3D modeller Artur Tchoukanov promptly figured it out, designed a 3D shape that accomplished the same thing, and uploaded his shape's specifications to Thingiverse, a repository for 3D designs.
Then I came along and missed the fact that there was a challenge underway, and erroneously credited Artur Tchoukanov with creating the shape. Schwanitz sent me some emails asking for correction, but they arrived while I was away from the Internet at a conference, so it was a few hours until I updated. In that time, Schwanitz sent Thingiverse a DMCA notice -- essentially, a threat to name Thinigverse as a party in any copyright lawsuit against Tchoukanov unless Thingiverse took the shape down immediately.
Whereupon Schwanitz became the inventor of something much more substantial than a 3D Penrose Triangle -- he became the inventor of copyright threats over open 3D repositories. A weekend's worth of acrimony followed -- with lots of speculation about the copyrightability of Schwanitz's design and questions about whether Tchoukanov was guilty of violating any copyright that vested in the design, and further questions about the ethics of copying designs and the ethics of sending copyright threats to Thingiverse.
Here's where I net out on it: the 2D Penrose Triangle is not a copyrightable image. It is in the public domain. It is possible to make new copyrighted works based on the public domain (see, for example West Side Story, a new copyrighted work derived from the public domain Romeo and Juliet). The copyrightability of such a work hinges on whether it is sufficiently creative.
I think Schwanitz's design is indeed creative, and probably attracts a new copyright. However, I'm not convinced that Tchoukanov's work violates that copyright, since it's not a "copy" of the Schwanitz design (that is, it wasn't created by copying the file), but rather, an interpretation of the underlying public domain work inspired by Schwanitz's design.
I further think that Schwanitz was wrong not to expect people to present solutions to his challenge in the form of 3D files. After all, if you pose a public mathematical riddle, you should expect the challengers to upload their equations in response. "Show your work" is a feature of all good scholarly pursuits.
But I also think I'm to blame for not parsing the post I reported on more closely -- I was in a hurry, and the context of the post on i.materialise was unclear, so I misattributed the work. This was compounded by one of those rare moments when I wasn't online, which is just sod's law in action.
Finally, I think that Schwanitz has done the right thing in dropping his complaint against Thingiverse and Tchoukanov's work -- not least because, as Thingiverse's Chylld has demonstrated, it's trivial to create new "impossible triangle" designs that are strictly based on the public domain image that inspired Schwanitz, which means that Schwanitz will never be the sole supplier of this particular 3D optical illusion (this is the other side of the public domain bargain: you may use it for free, but so many your competitors -- hence Disney has to contend with innumerable other versions of Rapunzel that compete with their Tangled).
All in all: fun times. Expect them to get weirder. I mean, aggrieved optical illusion creators don't have anything like the political and legislative clout of other potential 3D printing complexifiers. Imagine what happens when some magistrate in Alabama decides that Thingiverse is liable for hosting 3D models of sex toys (illegal in AL) and issues a bench warrant for Bre Pettis's arrest. Or when someone from Shapeways shows up at CES in Vegas, only to discover that the state Drug Enforcement Agency has issued a warrant on the basis of a bong design available at Shapeways, violating the state's strict anti-drug-paraphenalia laws. Or someone from i.materialise gets an EU extradition request from Germany because someone's printed a detailed, historically accurate toy soldier with a swastika armband, violating Germany's strict laws against Nazi paraphernalia.
And just wait until someone creates a printer that can reproduce patented pharmaceutical compounds or Monsanto's patented life-forms! Now there are a couple of villains with a lot of resources to throw at making the whole Internet's life miserable in order to squeeze an extra 0.05% into the quarter's bottom line.