3D printing is a way of making real objects from designs on a computer.
Rather than making something by sticking lots of small parts together, a 3D printer can build complicated items in one piece.
It's been used in the manufacturing industry for quite some time, but as the technology improves the possibilities increase.
3D printers are slowly becoming cheap enough for people to have a small one at home.
What can be 3D printed?
Typically 3D printers make items out of plastic. You could print a perfect-fitting case for your phone or even a replacement part for something broken.
3D printers can also make replacement body parts that are custom designed to fit your body perfectly.
Not all 3D printers use plastic. Some can be filled with chocolate to print fancy treats!
It's hoped that 3D printers will eventually have no trouble printing body parts made of real human cells.
Will home printing take off?
"Judging by the way 3D printers are used now, it's unlikely we'll all have one in our homes in the near future," said Newsbeat technology reporter Jonathan Blake.
He told Newsround: "Unless you're a designer or need to produce a lot of objects regularly, it's more likely that you'll go to a shop and get something printed."
"The equipment is getting cheaper though, and scientists are pushing the boundaries of what they can produce all the time," he said.