There are often multiple ways to get exposure to the same investing theme. To borrow from the oil industry, an investor can usually invest upstream or downstream, meaning she can invest directly in the technology itself, or the companies that are best positioned to benefit from said technology.

In the case of 3-D printing, an investor looking to get direct exposure to the space would invest upstream and buy companies like 3D Systems (NYSE:DDD) and Stratasys (NASDAQ:SSYS). If an investor wanted to buy into a company that benefits from 3-D printing, she could invest downstream and zero in on a company like General Electric (NYSE:GE), which has a massive manufacturing base.

Your strategy and risk tolerance will dictate whether it makes more sense to invest upstream or downstream. In the following video, 3-D printing analyst Steve Heller sheds light on these different strategies by exploring the merits of 3D Systems, Stratasys, and General Electric.