We will remember this photo as the photo that changed the world.
http://m.guardian.co.uk/commentisfree/2013/may/10/3d-printing-gun-blueprint-state-department-ban This photo shows a man shooting a gun manufactured by 3D printing. Forward ten years, and a lot of people will have access to a gun with no license number, albeit unreliable.
How does that change the world? Max Weber famously claims that states have "Monopoly on Violence". In the last few decades, we saw another monopoly disappear: The dissemination of copying technologies - say, photocopy machines and cassette tapes - eventually meant that the copyright holders' monopoly on their works disappeared. This happened because the copyrights were rendered ineffective by the new technology. It is then conceivable that the 3D printing technology will render the state monopoly on violence ineffective.
Perhaps this is not as ominous as it seems. Perhaps this is just another wave of creative destruction.