Shares of 3D Systems (NYSE:DDD) and Stratasys (NASDAQ:SSYS) popped today on news that Citigroup analyst Kenneth Wong initiated coverage of these two stocks with a buy recommendation. In this video, Motley Fool industrials analyst Blake Bos tells investors why analyst recommendations may not be a very sound reason to invest and takes a look instead at several things 3-D printing investors need to be watching with these two companies' fundamentals.

Blake Bos has no position in any stocks mentioned. The Motley Fool recommends and owns shares of 3D Systems and Stratasys and has the following options: short January 2014 $36 calls on 3D Systems and short January 2014 $20 puts on 3D Systems. 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.