Yesterday, I blogged about Artur Tchoukanov, who figured out how to make a 3D printed "impossible" Penrose triangle. Turned out I didn't have the details quite right. The guy who came up with the 3D design in Thingiverse had made it after seeing someone else's model for the same thing on Shapeways, and he'd made the triangle design to show that he'd figured out how the trick was done.
The person who invented this way of inventing this 3D Penrose Triangle was Ulrich Schwanitz, who sent me some emails asking me to correct my post (which I did as soon as I got back to my laptop after a day at a conference), but he sent a much more substantial email to Thingiverse, a service that hosts 3D models: in this email, Mr Schwanitz accused Tchoukanov of violating his copyright and demanded that the model be removed from the Internet in accord with the Digital Millennium Copyright Act.
In so doing, Mr Schwanitz has become the first person in history to threaten Thingiverse with a copyright lawsuit.