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 3-D printing technologist Stratasys (Nasdaq: SSYS) were flattened today, falling as much as 22.7% overnight on several times their average trading volume.

So what: The company is in the habit of beating analyst estimates senseless, preferably with a freshly printed blunt object. This time, second-quarter earnings did indeed exceed expectations, but revenues did not -- and retribution is often swift and merciless when you're priced for perfection to begin with.

Now what: Stratasys sat even higher in the nosebleed seats three months ago, before investors punished the company for an overpriced acquisition on the eve of another positive earnings surprise. In the meantime, the company has renewed an agreement that lets Hewlett-Packard (NYSE: HPQ) sell HP-branded Stratasys printers and also expands that partnership into several new European markets. Rival 3-D Systems (NYSE: DDD) fell more than 10% at worst on Stratasys' news and is set to report earnings tomorrow, so keep an eye on that report for a fuller view of the 3-D printing industry. Neither stock is exactly cheap today, but sometimes you get exactly the growth you're paying for, which is why our Motley Fool Rule Breakers newsletter team loves Stratasys and the Fool owns shares of 3-D Systems.

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Fool contributor Anders Bylund holds no position in any of the companies discussed here. The Motley Fool owns shares of 3-D Systems. Motley Fool newsletter services have recommended buying shares of Stratasys. 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 is investors writing for investors.