According to Wohlers Report 2015, a leading 3D printing insights publication, the 3D printing industry grew by a 35.2% year over year in 2014, which translated to $4.1 billion in worldwide revenue. Wohlers also estimates that the 3D printing industry is expected to generate more than $21 billion in worldwide revenue per year by the end of 2020 – an over four-fold increase from 2014 levels.

Unfortunately, investors who bought 3D printing stocks in the last couple of years thinking they would benefit from strong industry growth have been sorely disappointed. Top 3D printing stocks 3D Systems (NYSE:DDD), Stratasys (NASDAQ:SSYS), ExOne (NASDAQ:XONE), Arcam (NASDAQOTH:AMAVF), and voxeljet (NYSE:VJET) have all suffered catastrophic losses since the start of 2014.

DDD Chart

DDD data by YCharts.

The following presentation examines how 3D printing stocks have been moving in the opposite direction of the industry's growth trajectory.

Steve Heller owns shares of 3D Systems, ExOne, and Google (A & C shares). The Motley Fool owns and recommends 3D Systems, and Google (A & C shares). It recommends ExOne and Stratasys. 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.