Doctorow: The coming war on general-purpose computation

And how precisely do you intend to do that?

Today, you can buy or build any number of 3D printers or milling machines for solid objects, supporting plastics, metals, wood, and various other materials. In addition to building anything you design yourself, you can download ready to use plans for any number of objects online; they just consist of a pile of bits, and as we've already established you can't actually control the copying of bits without limiting general-purpose computers. As mentioned in the article, people have used 3D printers to print the key parts of weapons. Or to look at a different angle, nothing stops you from printing a patented mechanical design.

We don't necessarily have the technology today to just attach a USB device and start printing off DNA, but we will. What makes that any different, or any more meaningful to regulate, once we have that technology readily available? Either way, you just have a stream of bits that some people don't want distributed or used.