In the coming years, a number of factors will likely make life more difficult for some of the biggest names in 3-D printing today.

For 3D Systems (NYSE:DDD) and ExOne (NASDAQ:XONE), expiring patents will open some key elements of their technologies, which will not only invite the threat of new competition, but also put pressure on their revenues due to the increase in potential competition. For Stratasys (NASDAQ:SSYS), the company remains committed to its Fused Deposition Modeling technology, putting its business at risk from the threat of superior technologies emerging.

In the video below, Fool.com contributor Steve Heller explores these risks, assesses how each company could mitigate the threats, and looks at some some things to consider if you're invested in the space.