The state should refrain from imposing bans  In Western liberal democracies, we generally consider an individual’s private sphere to be worth protecting. We only give the state license to violate it when something is objectively largely harmful to that person or to society. When something is not very clearly harmful we let people make their own decisions because the state is not infallible in its judgements about what lifestyles are better than others.  Therefore, simply saying that there is a risk that printers will be misused is not sufficient grounds for banning them altogether. If technology makes it easier for people to do what they want, this is a good thing; if people then want to do things that we consider harmful this is a problem in itself. The solution is not to ban an entire means of production in order to stop a minority from producing dangerous things, but to educate people about the risks so they can freely make better decisions. Making it harder for people to do bad things is useless, furthermore, since those that wish to purchase a gun or take drugs can already find ways of doing so without 3D printers. One may even argue that it is better for everybody to have access to a gun, for example, and not only those who are willing to break the law to get one.