The first time I saw a 3D-printer in action was at the science park in Lodz, Poland. The printer was a testbed for the science park, acquired to attract an eco-system of startup´s who would innovate using the technology.
Earlier this year, it was reported in the news that a construction firm in Shanghai has developed a house which can be mass produced using a giant 3D printer.
A few weeks ago I attended a seminar in Stockholm which related to the sharing economy, that is, peer-to-peer-based sharing of access to goods and services, often coordinated through community-based online services, and I was told examples of how 3D-printing allows for new business ideas.
This morning I read on the web that the Dutch company MX3D are about to 3D print a steel bridge. See below a brief video about the project. This new technology is really coming of age.