I believe people should be able to buy 3D printers. I don't understand why we would develop a product and then not make it available to consumers. I have my doubts 3D printers are ready for the consumer market but there will come a time in the future when they will be.
People should be able to buy 3D printers. This is an amazing technology that will one day revolutionize everything. I hope one day that they are cheap and that everyone owns one. If people start getting them, then they tinker, and that's how the technology will really rise at an exponential rate.
If 3D printers can be used in a way which is unethical or illegal, then purchase of the printers by the public shoudl be conditional on their ethical use of them. If there is concern that the will be able to print objects of things of an illicit nature, printers can be developed so that the the content of the printer can be obtained via a warrant.
People should be able to buy 3D printers. However there should be laws on the books making it illegal to manufacture or print guns in you home. There are many useful things that people can print with 3D-printers, such as prosthetic limbs. 3D printers are very expensive right now so only a small group of people can afford to buy them anyway.
This question is one that many people have been asking for a very long time because the subject matter is not one that is easily answered. There is a large group of people that believe the answer is simple and a quick resolution can be had. But that is not the case in this situation.