And then, of course, there's the Chinese wild card. The Chinese government and Chinese industry certainly aren't blind to the future of 3-D printing or its capacity to profoundly reorder the world's manufacturing economy.
There's ample evidence that China's government has targeted 3-D printing as a key future technology. For example, a Beijing University research team, working on 3-D production for aircraft parts, won a national award from the State Council for Technological Achievement in January.
Given how important this technology is likely to be and the extreme difficulty in calling a winner at this stage, I think investors have two choices.
First, in the short term, you can simply trade these stocks as you would any hot momentum play. Buy and sell as the short-term trend indicators suggest. This won't give you a lasting or increasing exposure to the sector, but you will stay on top of trends and, to the degree that you aren't a purely technical trader of these shares, you'll gradually increase your familiarity with the companies in the still very early stage market.
Second, you could take a more long-term, venture capital approach and put together a portfolio in the sector. Venture capitalists expect that of 10 bets they make, some will simply not play out and may actually lose money; some will do no better than break even; some will result in a two- to three-fold return; and a very few will turn into a seven- or eight- or even a 10-bagger.
The keys to making this approach work are:
  • Even though you are building a portfolio, you still do due diligence and try to pick the best companies in the sector, given your understanding of the limits of your knowledge.
  • You make sure that your portfolio truly covers all the bases in the emerging sector. If the future surprisingly zigs, you'd like to own a piece of it.
  • Price matters. It's a whole lot easier for a $500 million market-cap stock to turn into a $5 billion market-cap stock than it is for a $10 billion market-cap stock to go to $100 billion.

Building a 3-D portfolio

To build my 3-D portfolio now, I'd like to include the three stocks highlighted above, with an idea of buying some ExOne now and more later if the shares drop on the end of post-IPO lockups that prevent selling by insiders and early round investors. I'd like to get 3D Systems cheaper than it is now, but I wouldn't wait for it to get absolutely cheap. It and Stratasys are volatile, and I think you'll have plenty of drops for buying both.
And, of course, keep your eyes open for new entrants into the field that deserve a place in your sector portfolio.
Like most truly disruptive technologies, the 3-D printer story isn't all sunshine and lollipops, from a macro perspective.
First, the technology will eliminate high-paying manufacturing jobs. A company might indeed save money by using 3-D printing technology to prototype and produce complex components, but that will also result in the elimination of highly skilled practical engineering and production jobs.
Long term, I don't know if the new jobs created in software design, for example, will balance out the jobs lost, but it's clear that the skilled workers who lose their jobs because of the adoption of this technology won't be hired for the new jobs created by this technology. In other words, 3-D printing technology will clearly worsen the problem whereby older skilled workers in relatively highly paid jobs lose those jobs and lack the skills required by newly created positions.
Second, 3-D-printer technology will make the inadequacies in the world's apparatus for protecting intellectual property even worse. How do you protect a design when software engineers can turn it into code, and then either print the product themselves or put the code on the Internet for all to print? And when a "unique" product exists as code, then what exactly are the criteria for intellectual property that are eligible for protection?
The global economy never works out the solutions to problems like these before a disruptive technology is let loose on the world. And there's no reason to think that we'll do better this time.
3-D printing is coming. It is the future. The big questions are what that future will look like and how long it will take to arrive.