File-sharing site The Pirate Bay caused an Internet stir last week when it introduced a new content category called "Physibles," essentially designed to allow people to pass one another physical objects for download. The term refers to data files that are actually able to become physical objects via 3D printing technology.

Before long, The Pirate Bay said in a blog post, "you will print the spare parts for your vehicles.”

Some saw the announcement as an overhyped publicity stunt. Others saw a powerful revolution of how humans acquire essential goods. But one expert Mashable spoke with this week said that 3D printing is indeed bound for the mainstream — and even sooner than The Pirate Bay might think.

"If you want to draw that parallel, we are kind of in the early 1980s of the computer industry right now, when it was just moving from mainframes into home computers," said Hod Lipson, a Cornell University associate professor of both Mechanical & Aerospace Engineering and Computing & Information Science.

"I see a big future for 3D printers in personal-scale applications that will unfold over the next decade."

That big future will probably include kids like Riley Lewis and Vernon Bussler (right and left, respectively, in the accompanying photo).

Riley and Vernon are eighth graders. Along with a small cohort of classmates at Discovery Charter School in the Bay Area, they're already getting pretty deep into the world of 3D design and printing. After Riley developed a strong interest and aptitude for 3D printing a couple of years ago, a company called 3D Systems donated a 3D printer worth several hundred dollars for him to use at school.

The class of some dozen students is one a very small number of middle school labs beginning to delve into the emerging industry. The group's work has been featured in a Popular Science blog post, and they have already produced items including dice, jewelry and replacement parts for the printer. Their progress reflects a tangible future for the medium that exists outside of exclusive laboratories and research facilities.

"It's just amazing to have an idea and then be able to create a perfect rendition of it, something you can physically hold and touch," Riley told Mashable.

Vernon said that their classmates react with "a combination of 'that's cool' and 'I don't get it.'"

According to Lipson, more and more people will begin to "get it" in the coming years.

"When you unleash this capability to make physical objects in any shape or form, the implications are tremendous in nearly every aspect of our lives," he said.

In its blog post announcing "Physibles," The Pirate Bay claimed that "You will download your sneakers within 20 years."

But that will actually happen "a lot sooner," said Lipson, who co-authored a report on printing physical objects for the White House's Office of Science and Technology Policy.

Lipson said he foresees 3D printers existing in a variety of different scales and applications. Machines at home might produce food and toys. (A team led by Lipson unveiled a food printer last year.) Neighborhood centers analogous to Kinko's or Home Depot might provide more high-end services. And specialty shops might print their own replacement parts, for example an auto body shop printing spare car parts.

Meanwhile, kids like Riley and Vernon will continue to passionately tinker away, not dissimilar to how home enthusiasts helped high-powered institutions develop the computer decades earlier. Riley said he is especially enthusiastic about pursuing the printing of physical objects into college and beyond.

But what does Riley most want to print right now? "Another 3D printer," he said.

What do you think the future holds for 3D printing? What do you most want to print at home? Let us know in the comments.

Photo courtesy of Dave Lewis