Although we don't believe in timing the market or panicking over market movements, we do like to keep an eye on big changes -- just in case they're material to our investing thesis.

What: Shares of ExOne (NASDAQ:XONE), a maker of 3-D printing machines and provider of 3-D printing services, jumped as much as 12% after reporting its fourth-quarter results and providing its 2013 forecast.

So what: For the quarter, ExOne sold eight 3-D printing machines, drastically pumping up revenue to $12.7 million and allowing the company to reverse a year-ago loss of $2.8 million into a $0.9 million profit. Machine sales represented 70% of total sales during the quarter and management noted that customer acceptance of its newer machine models and strength in industrial 3-D printing demand drove its results. Looking ahead, ExOne sees revenue growth in a range of $48 million-$52 million, with two-thirds of that revenue expected to occur in the second-half of 2013. Gross margin should land between 42% and 46%.

Now what: Congratulations to ExOne on its profitable quarter, but my resolve that it's grotesquely overvalued still stands. ExOne fills a niche by handling larger industrial 3-D printing that popular play 3D Systems (NYSE:DDD) just can't satisfy with its focus on smaller, consumer-oriented products. However, even with this niche advantage, ExOne still only has produced 21 machines in 12 quarters (it takes quite a bit of time to produce those machines) and has just a few global companies comprising their largest customers. This could leave it very exposed to an economic downturn, or even stagnation. Let's be clear: I'm not a fan of any 3-D printing companies here, but if you're looking to get industrial-focused exposure, Stratasys (NASDAQ:SSYS) appears to be the smarter play with the specialization capabilities it's acquired because of its merger with Objet. I'm just saying, don't be shocked if ExOne is right back in the loss column again next year.

Craving more input? Start by adding ExOne to your free and personalized Watchlist so you can keep up on the latest news with the company.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.