Shares of 3-D Printing companies had a wild ride at the beginning of the week. Stratasys (NASDAQ:SSYS) and ExOne (NASDAQ:XONE) shares were both down by as much 10% Monday, while shareholders of 3D Systems (NYSE:DDD) watched their holdings drop as much as 8%.

In this video, Motley Fool contributor Brian Stoffel explains what caused the drop, and why long-term investors need not worry about recent volatility.

Fool contributor Brian Stoffel owns shares of Stratasys. The Motley Fool recommends 3D Systems, Stratasys, and The ExOne Company. The Motley Fool owns shares of 3D Systems and Stratasys and has the following options: Short Jan 2014 $36 Calls on 3D Systems and Short Jan 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.