On a high level, 3-D printing is relatively easy to understand: It's an additive manufacturing process that builds objects in a layer-by-layer fashion. However, the nuances of investing in the space may be confusing to some.

For instance, Germany-based voxeljet (VJET 14.62%) trades in the U.S. with American Depositary Shares, and each ADS represents one-fifth of an ordinary share. As a result, financial portals like Yahoo! Finance often misprice the company's market cap by a significant factor. Because many financial valuation ratios use market cap as an input, it's extremely important for investors to know how much voxeljet is actually worth before starting to assess its valuation.

To calculate voxeljet's real market cap, multiply the value of each ADS by five, and then multiply that result by the number of ordinary shares outstanding, which is currently 3.12 million. At a present price of about $35 per ADS, voxeljet's market cap is roughly $546 million.

Additionally, selective laser sintering, or SLS, and electron beam melting, or EBM, are two competing 3-D printing technologies that appear awfully similar, but are technically significantly different. SLS uses a laser to selectively heat and melt fine powders into objects, while EBM uses an electron beam to accomplish the same thing. As a result, SLS excels at creating more detailed parts than EBM, but the cost per part is significantly higher. SLS was invented by 3D Systems (DDD -0.86%) and EBM was invented by Arcam (NASDAQOTH: AMAVF).

In the following video segment, 3-D printing analyst Steve Heller discusses with Blake Bos, head of Motley Fool's industrials sector, these two common 3-D printing misconceptions. (The relevant segment can be found between 17:01 and 20:42.)