Nokia and MakerBot are in Barcelona this week for the Mobile World Congress. The companies have teamed up to offer what it calls the "first live social 3D printing experience." In short, MakerBot is creating custom Nokia Lumia 820 cases on the show floor for attendees.
As you can imagine, this isn't the first time 3D printers have been used to make smartphone cases. A quick search on Thingiverse for "iPhone case" returns 591 results. 3D printers have also been used to make some rather interesting designs, like a steampunk gear case or a sweater case.