The upward run of 3-D-printing stocks can largely be attributed to hype rather than to an imminent revolution in consumer technology, according to analysts.
(Read more: What investors need to know about 3-D printing)
"The 3-D-printing industry isn't revolutionary, it's evolutionary," said Andrew Left, a notable short seller and chief of Citron Research. "In a hot market like this, you get a good story. It just captures peoples' imaginations, but in this case it also captures peoples' dollars."
While the technology has been around for more than 30 years, the industry has received an enormous amount of attention with the recent availability of consumer printers—a shift that has helped drive up stock prices, according to industry experts.
For example, 3D Systems' stock price has risen more than 120 percent during the past 12 months. Stratasys shares have jumped more than 98 percent, while those of Voxeljet and ExOne also have got significant boosts.
But investors should beware, as not all 3-D-printing companies are created equal, said Phil Reeves, managing director of Econolyst, a consulting and research firm.
"When you look at these stocks, they all appear to be intrinsically linked," he said at the 3-D Printshow in New York earlier this month. "When one goes up, the others go up, and when one goes down, the others go down."
(Read more: 3D Systems profit warning rekindles fears of printer bubble)
But, he added, "when you map out their business models, some of them have nothing to do with each other as businesses. And they have very different business dynamics and different customer bases."