The first month of this year hasn’t particularly kind to the market as a whole, but it’s been downright cruel to 3D printing stocks.

While the S&P 500 ended Wednesday down 4.1% for the year so far, shares of three-dimensional printing favorite 3D Systems (DDD) are off by 16% since the end of last year. Stratasys (SSYS) is off nearly 13%, while ExOne (XONE) shares are down 21% year-to-date. Yes, it’s been a rough start to the new year for some of 2013’s biggest winners, thanks to a couple of earnings warnings from key players in the industry.

Yet veteran investors know that, sometimes, the best time to go bargain hunting is when it looks like a stock and its peers are completely out of favor. There’s no doubt that tickers like XONE, DDD, and SSYS fall into the “out of favor” category right now. The question is, are 3D printing stocks an underestimated and unappreciated bargain here, ready to rebound in the foreseeable future?

Answer: It depends on the company in question.

In no particular order, here are the buy/sell calls on the five biggest 3D printing stocks.

3D Systems Corporation (DDD)

As easy as it is to presume the biggest player in an industry is the also the best, $8 billion printer manufacturer 3D Systems Corporation (DDD) doesn’t fit that mold.

It’s not a matter of capability; 3D Systems makes great three-dimensional printers. At some point, though, the market is going to realize that the value of DDD stock has far exceeded any reasonable likelihood of being justified in the foreseeable future … even if the industry’s growth reaches the top end of expectations. As of right now, 3D Systems Corporation is priced at 169 times its trailing earnings, and at 61 times its forward-looking earnings.

Being one of the premier 3D printing stocks also means you’re the biggest target for the naysayers. Case in point: Citron Research recently published a long string of reasons investors would want to steer clear of DDD stock. For better or worse, people pay attention to — and respond to — that kind of commentary. Perhaps worse than that, some of the media began to circulate those arguments.

Now that it’s on traders’ mental hit list, it’s going to be tough for 3D Systems to shrug off the stigma.

Voxeljet AG (VJET)

From a price of $34 at the end of October to a high of $70 in November, back to a low of $34 in December, Voxeljet AG (VJET) has been all over the map. Unfortunately, even at the low end of its recent range, Voxeljet is going to have a tough time justifying its recent share price.

Voxeljet makes and sells 3D printers, but the company isn’t relying on sales of printers to be the key driver of revenue and growth going forward. VJET is aiming to become a service provider, printing three-dimensional goods for firms and companies that don’t have their own three-dimensional printer to do the work.

To be fair, the prompt for the run-up was an impressive 77% increase in its third quarter revenue following a couple years’ worth of not-too-shabby growth … not to mention a huge backlog of orders that was actually greater than Q3’s total sales. The price of VJET stock has been rightfully lowered in the meantime, but the stock’s still more of a speculation than an investment. And, priced at 358 times its forward-looking earnings, it’s a speculation with the deck stacked against it.

Throw in the ironic fact that 3D printers have become so affordable that a need for a three-dimensional printing service is now in question, and Voxeljet AG just poses more risk than it’s worth compared to other 3d printing stocks.

Stratasys Ltd (SSYS)

Stratasys Ltd (SYSS) may not be the biggest player (in terms of market cap) of the 3D printing stocks, but it’s arguably the best 3D printer maker out there … and that’s saying something, considering its support and supply divisions are a huge part of its revenue engine.

For example, Stratasys recently unveiled the world’s first multi-material 3D color printer. Some are calling it the best three-dimensional printer yet. At the same time, Stratasys’ MakerBot line of 3D printers were recently added to Dell’s lineup of third-party products.

Putting it all together, what you have is a company that’s happy to be in second place in terms of size and expectations among the major 3D printing stocks. That keeps the target off of its back.

SSYS stock still isn’t cheap at a forward-looking P/E of 53, but it’s palatable compared to 3D Systems and other 3D printing stocks, and its product base is healthier.

ExOne (XONE)

If there was one company the market could point to and say it was the cause for the meltdown for 3D printing stocks as a group, it would be ExOne (XONE).

Yes, ExOne and Stratasys both warned in mid-January that they would miss fourth quarter estimates, but ExOne did most of the damage. Although CEO Kent Rockwell said the Q4 shortfall was only a timing issue and not a demand issue, analysts read between the lines. Credit Suisse reiterated its underperform rating on XONE stock, while Canaccord Genuity lowered its rating on the stock from a buy to a hold.

Investors should heed those warnings and avoid XONE stock.

Camtek (CAMT)

Though Camtek (CAMT) has been around for years, it didn’t become one of the key 3D printing stocks until November when it announced it would introduce a printer capable of fabricating printed circuit boards.

It sounds too advanced to be true, but truth be told, the complexity and technology behind the solder mask technology may have been a tad hyped. Either way, the process is proven, and could truly change — by lowering the cost — the way electronics makers perform low-quantity production runs.

It’s still the riskiest of the five 3D printing stocks under the microscope, as there’s no actual production of its circuit board printer yet, and no absolute guarantee one will go into production. But, CAMT stock is making forward progress.

Even without the help of a great deal of news from the company, that momentum paired with the mere possibility of a mass-production circuit board printer generates enough of a bullish undertow to make Camtek worth a shot … for the higher-risk portion of portfolios.

As of this writing, James Brumley did not hold a position in any of the aforementioned securities.