The 3-D printing “will do for physical objects what MP3 files did for music,” wrote Deven R. Desai, associate professor at the Thomas Jefferson School of Law, and Gerard N. Magliocca, professor at the Robert H. McKinney School of Law at Indiana University.

But just as people copy music files, it seems probable that they will do the same with objects — a tool, say, or a piece of furniture that may be covered by a patent. All patents are available to the public, and it would be possible for a knowledgeable person to pore over a patent file and create software that can reproduce the invention described, Professor Desai said. Also, 3-D scanners can scan some objects and translate them into computer models, to be modified or printed.

Just as record companies were unable to stop music file-sharing, manufacturers will not be able to prevent the proliferation of 3D printing users, he said. While violation of patents is a concern, and there may be ways to sue some individual lawbreakers, the best way to handle this threat, he said, may well be to embrace the new technology and the new markets it opens.

People who use unauthorized music-sharing sites know that the files they download may be poor in quality or corrupt, or even contain viruses; that’s why they are willing to pay for their music on sites like iTunes. Similarly, manufacturers can set themselves up as authorized dealers for 3-D software and material, Professor Desai said, so that “consumers would know they were getting a trusted product.”

A main advantage of 3-D printing is that users can customize items to their personal needs — for example, by adjusting the sizes and shapes of parts. Manufacturers could customize their mass-market products for people using 3-D printers and promote them as having superior quality, Professor Desai said.

Is the government likely to take an aggressive approach toward 3D printing violations? That’s hard to know, but past efforts by the government to stop illegal taping of movies and television shows, along with illegal downloading of music, have not been very effective, and the same seems likely to be true of 3-D printing, Professor Desai said. The march of technology is just too insistent.