The progress in 3-D printing has been nothing short of astounding over the last decade. The soaring stock prices of publicly traded 3-D printing companies 3D Systems (NYSE:DDD) and Stratasys clearly illustrate the industry has made advances. Today, even consumers can get their hands on a plastic 3-D printer at a reasonable price -- an unheard-of possibility just five years ago. This phenomenal industry progress has led some to believe Moore's law applies to 3-D printing. Are they right? One inventor in Colorado disagrees.

Moore's law? Not really
At the Inside 3D Printing conference in Chicago this year, 3D Systems CEO Avi Reichental asserted that Moore's Law applies to the 3-D printing industry. For those not familiar with Moore's Law, it is the observation that the number of transistors on integrated circuits doubles approximately every two years and that this trend should continue in the future. Intel co-founder Gordon Moore famously pinpointed the trend in 1965.

"Printers are going to double up on performance and double down on costs. Expect printers to become real powerful home appliances. The train has left the station," Reichental proclaimed at the Chicago conference after relating the industry progress to Moore's law. But just because the law has held true for transistors on integrated circuits, it doesn't mean Reichental's bullish outlook will hold true for 3-D printing technology.

When I recently interviewed David Hartkop, the creator of a just-unveiled prototype of the world's first desktop printer for printing metal at home, the Mini Metal Maker, I asked what he thought about Reichental's prediction.

Moore's law or not, the industry's progress is astounding, and it likely will continue to be impressive. But investors would be wise to listen to Hartkop and not model their expectations after Moore's law. 3-D printing comes in many forms, based on many different technologies, and it's a very physical process; the Moore's Law analogy is likely unrealistic.