3D printed body parts? Anyone tried?

As a guy who has a 3D Printer and used them in almost all of my jobs. You would need a very large (and expensive) 3D printer and the print time would be quite extensive. Similar to composites, the material isn't necessarily the expensive part, it's the time. On another note, 3D printers print in layers and those layers wouldn't necessarily follow the profile of your "sheet metal" panel. As you print, you have to generate support structures to support your build as its building. Those support structures can be an enormous pain to remove. So, you could have a lot of surface finish issues and in some areas your panels would be susceptible to shearing easier than a metallic or composite body panel.

On that note, I have dabbled with designing and printing parts on my Dart at home. That part takes a lot of time, but it's challenging and fun. My printer can print within a 10" x 10" x 12" volume which limits the bigger car stuff to print.