I had read about this in Popular Science awhile back. If these things can be made in such a way that mother nature tends to break things (earthquakes, rain, snow, ice, hurricanes, etc etc...) and lay down material as strong as reinforced concrete, then why the hell not! The sky's the limit. Now just have to figure out how to get the re-bar into the structure... I guess they could just make a mold, then pour the concrete inside.
Looks like my dreams for an evil lair are going to come true after all... Now I wonder if he can print out sharks with lasers on their heads.