DOMA and its ilk are abominations, and it is revealing that when it comes to equal marriage the libertarian hoards, who demand the right to have weapons that slaughter, are nowhere to be found.

For the vast majority of primate evolution, our ancestors lived in "bands." That is, groups that produced no surplus above subsistence and reproduction, and moved to where ever living was best. Approximately 600,000 years ago, our ancestors started developing much higher brain capacity, and 100,000 one several different possible configurations began develop language. Thus virtually all humans have language acquisition skills, and the ability to deal with a moderate set of individuals they are in contact with, along with the ability to acquire understanding of acceptable range of behavior within that group – that is, morality.

Only about 15,000 years ago did we start living in groups larger than a "band" and only about 12,000 years ago did we successfully domesticate animals, which means the ability to look ahead at the results of today's decisions. Permanent markings with meaning are roughly 9000 years old, writing, at best, 6000 years old, and more probably less. Thus while these abilities are highly selective, there are going to be people who are unable to learn to be functionally literate, and are unable to understand ethical implications. There just has not been time for these mechanisms to both be selected for, and for their absence to be as notable as being unable to learn language and morality.

In our present circumstance, for the last 200 years one means of imposing ethical control, however imperfect, was prior restraint through capital. This is only because during that time were capital goods large enough to be expensive, and effective enough to reliably defeat personal capital, the kind one person could make with personal tools, at least under specific conditions. As the sphere where expensive capital could dominate grew, so too grew the power of centralized capital, including a centralized capital driven market-state. The state encourage economic growth, and directed it in ways that produced technology useful to the state for war. In a nutshell, this is Adam Smith's argument in Wealth of Nations: allow individual market behavior, but restrict capital accumulation of certain kinds, and the result will be a more powerful nation state.

However, personal capital has jumped up considerably in the last century. The first examples are now more than 125 years old: telephones, which allowed individuals with no special expertise to communicate over long distances, and automobiles, which allowed people to move along a network at the rate previously reserved for large capital, trains. The states that barred these technologies, were conquered. The states that attempted to use ideological control, lost two waves of military and revolutionary conflicts. Thus came an era of "industrial regulation," regulating industrial capacity and use. Modern copyright, for example, is an industrial regulation. Some industrial regulations failed utterly, for example, prohibition of alcohol. The ones that worked, worked because the bar to making something was high enough, that controlling a small number of people was enough. Alcohol and Marijuana failed because brewing is easy, and distillation not that much harder, growing marijuana is almost too easy for words. In fact, it's difficult to get rid of it once it gets itself established.

The present, where reproduction, once expensive, and specialized production, once limited to skilled individuals, are joining the capital set shouldn't surprise anyone, increasing the power of personal capital has been the direction of societies for hundreds of years, at least since medieval agricultural and military innovations – e.g. longbow, stirrup, moldboard plow. More people with more capability means a more resilient society.

This is also why "pre-civilized" thinking says in the gene pool: much innovation, and virtually all exploration, comes from people who cannot, or will not, or are able not, to function inside the civilized, productionized, core. An English gentleman who tries to find the Northwest Passage in 1750, will be found as a frozen corpse. The rhetoric of evading the state etc. is part and parcel of that. Attacking it is pointless, you might as well outlaw being left handed. The challenge for the civilized majority, and most people are meant to live what Aristotle called "the polis," is to find ways of codifying ethical necessity as morality, and sorting the empowering uses of technology from those which are simply attempts to upset Nash equilibrium for personal gain.

It has been possible for a long time to make an automatic weapon with available tools. That's how they were invented in fact. What printing does is move this from a high skill slow activity tied to specific tools, to being a low skill generally performable activity. That challenge means that rather than being able to watch a few people with very specific signatures – that is, having gunsmithing ability and tools – to teaching people generally not to engage in certain activities. There's no evolutionary revulsion against shitting in public, or sneezing. We teach children to limit these things because they have ripple effects. The same is going have to be true here. We are, presently, doing a pitiful job of it, and even encouraging dangerous behavior. The massacre in Newton was conducted with legally acquired fire arms and ammunition acquired through the usual channels. It wasn't a failure of industrial control or regulation.

What this means is a shift from industrial regulation, that is prior restraint, to post hoc enforcement. Harder, less fool proof, and just about inevitable. The cat is out of the bag, and industrial control is going to fail in this. However, what will work is preventing people from getting rich on it. If someone wants to print out a firearm, there isn't much harm done. It's when someone rolls into town, prints up clean guns for organized criminals, and drives away with untraceable, but fungible currency that one is in more trouble. There will always people "free riders" trying to be parasites on the system. We should be more concerned with those that are near the core of our system (e.g. bankers, pwned regulators, billionaires) than people on the margins.

Not novel, not original, prior art, obvious.

NYC population density 27,532 sq/mi

And for less than the price of the next wall street driven financial crash.