Last week, 3-D printing bear Citron Research issued its second report in a year about how 3D Systems (DDD 2.31%) is grossly overvalued and assigned it an "immediate" price target of $56, when stock was trading around $80 a share. While Citron brought up a lot of good points within its 18-page report (PDF link), there were two areas 3-D printing analyst Steve Heller took issue with.

The first was that Citron claimed 3D Systems' Cube 3-D printer hasn't been well received in the marketplace, but it bases this claim on an older generation product, the Cube 2. Expected later this year, the sub-$1,000 Cube 3 will be more capable, easier to use, and affordable than ever before. Because Citron is basing its claims on past results, this reasoning may not continue to hold up well in the future.

Additionally, Citron made the claim that 3D Systems' service bureau is a "low-margin business with low barriers of entry," which isn't necessarily the case when you look at the numbers reported in the company's filings and recognize that a high level of expertise is needed to operate these sophisticated machines.

In the following video, Steve Heller sits down with the head of Motley Fool's industrials sector, Blake Bos, to discuss these issues at length and why investors may want to take these aspects of Citron's report with a grain of salt. What's more, Steve and Blake shed some light on whether or not 3D Systems deserves such a high premium over Stratasys (SSYS 0.96%). The relevant segment can be found between 9:05 and 14:22.