Shares of 3-D printer company ExOne (NASDAQ:XONE) sold off sharply today, down 9% after announcing earnings yesterday for what turned out to be a very bad quarter. Printer sales were down 22% year over year for the fourth quarter of 2013, with revenue for the full year coming in at $40 million, a full $10 million short of what the company had guided for. The company also gave weak guidance for 2014.

While it may seem like a shocking metric to hear that the company only sold a total of 12 printers for the entire quarter, investors should keep in mind that these printers are bought by extremely high-end industrial customers, with some models selling for more than $1 million apiece. In this video, host Mark Reeth talks to Motley Fool analyst Simon Erickson about ExOne and whether the growth thesis for investing in this stock is still intact.

Simon points to a number of ways the company is reinvesting in its business at the moment, growing the number of full-time employees by 45% last year, and adding another production service center, which are moves that he thinks will drive revenue growth for the long run despite the tough quarter and difficult 2013. Simon thinks the stock is definitely a buy today and predicts strong long-term growth ahead for the company in spite of this short-term rockiness.

Mark Reeth has no position in any stocks mentioned. Simon Erickson owns shares of ExOne. The Motley Fool recommends and owns shares of ExOne. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.