What happened

Shares of 3D prototyping company Proto Labs (NYSE:PRLB) joined a broad rally among 3D printing stocks of all stripes Thursday, rushing ahead to close the day up 13%.

So what

In the absence of any other news, Proto Labs' share price strength appears to trace back directly to preliminary fourth-quarter earnings results published by 3D printer maker 3D Systems (NYSE:DDD) this morning.

In that announcement, 3D Systems noted that sales for the fiscal fourth quarter seem likely to land at least 21% higher than analysts had forecast. What's more, the company says it might finally break a string of quarterly financial losses that has stretched back, uninterrupted, for four straight years.

3D printer

A 3D printer. Image source: Getty Images.

Now what

So an announcement like that might make investors in other 3D printing stocks feel just a bit more optimistic about their own chances. And even if 3D Systems' good news doesn't spread to other stocks in the sector, here's another reason for optimism:

Unlike 3D Systems, Proto Labs itself has been profitable for every year of its existence as a publicly traded company. And that's an even better reason to like the stock than anything 3D Systems might have to say.

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.