Quotation marks can be used to indicate that the phrase is not literally true. The writer is using the words as an analogy. Or, the writer is inventing a phrase. Or, the writer is repeating a phrase but is saying "I've seen someone else use this phrase this way, but I'm not sure it is usage." 3D printing is new. The technology itself is somewhat similar to the technology used to print words in ink on paper, but it is not putting words on paper and isn't what "printing" means... or, at least, meant in the past. The phrase "3D printing" is so common and accepted that it can be used without quotation marks. In computer parlance, when we are talking about words in ink on paper, we talk of "printing" or a "printout" or "printing out." 3D printing is so new that words and phrases to describe it are being invented, and usages are uncertain. The implied meaning is "since we call it a 'printer,' I guess you would call this 'printing out.'" The strangeness of calling it a "3D printer" has worn off, but the strangeness of saying "printing out" a solid object has not. The phrase emphasizes the magic and novelty. We do not think it is amazing to print out a color picture of a plate, but it seems amazing to "print out" a plate itself.

In this case, quotes are simply used to emphasize the phrase because it is a very unusual concept. Normally you would never think about the phrase "print out" being associated with dinner plates. So the author uses quotes to bring special notice to that unusual connection .