My opinion on 3-D printing can best be described as "evolving." I consider this a good approach when dealing with a technology still very much in an evolutionary stage. Sure, 3-D printing pioneers 3D Systems (NYSE: DDD) and Stratasys (Nasdaq: SSYS) have both been around for more than two decades, and their high-end machines are being used for an ever-growing variety of industrial purposes. But for nearly all of those two-plus decades, the average person would have had no idea what 3-D printing actually is, or what its capabilities are. Most still don't -- but that's changing fast.

The biggest evolutionary leap in 3-D printing hasn't been in terms of resolution, print speed, or software accessibility, although all of these elements have helped create the leap I'll discuss today. Stratasys and 3D Systems aren't even on the vanguard of the latest shift, which is part of a multiyear effort by upstart manufacturers to bring the capabilities of industrial 3-D printers to home desktops around the world.

You're about to hear a lot more from the media about the transformative power of 3-D printing, and a lot of it will focus on this 3-D-printing-at-home movement. But what does it really mean? What does it say about the future? Will this shift help or hurt the current industry leaders?

Answering these questions requires more analytical finesse than simply projecting exponential adoption curves out to infinity, because a 3-D printer doesn't have any easy analogues in our lives. It's not at all comparable to a paper-based 2-D printer, which has a simple function and can handle it at low cost. It's not like a computer, which can be miniaturized, networked, and augmented with complementary technologies over time to become something essential and portable, like a smartphone or a tablet.

While I remain optimistic about the long-term industrial adoption of 3-D printing, it's in-home use that's forced my opinion to evolve. Keep an open mind and read on, and perhaps we'll reach a deeper understanding together than we would have doing this sort of research alone.

Chronicling an evolution
In the interest of full disclosure, here is a quick rundown of my evolving analysis on in-home 3-D printing adoption:

Of course, with any evolving technology, one's views can always use some updating as the situation changes. That's where we stand today, thanks to two recent updates that have forced me to again recalibrate my thoughts. A Wired cover story, released earlier this month, delves deeply into MakerBot's new Replicator 2, a stylish $2,200 home unit that purportedly marks MakerBot's "Macintosh moment." However, a Kickstarter project to fund start-up Formlabs' new Form 1 3-D printer might represent an even bigger step forward in home adoption.

Challenges, threats, and opportunities
MakerBot represents a threat to, and an opportunity for, the established market leaders. The company raised $10 million last year from a group of investors that included Amazon founder Jeff Bezos to become the brand you recognize if (or when) you decide to pick up a 3-D printer for your own home. Forget 3D Systems' Cube -- the Replicator 2 offers two and a half times as much three-dimensional space to build objects with a resolution that's up to 60% more precise. It costs nearly twice as much as the Cube, but you can easily make the argument that early adopters are more concerned with features than with price points.

It's a threat because 3D Systems has not put its weight behind home adoption and risks losing out on industry leadership if home use takes off. Consider the Replicator 2's cost. If MakerBot can create next-gen Replicators of the same quality for half the price, it could build a billion-dollar business from a million sales to home users. The $10 million funding MakerBot received last year is supposed to, in Wired writer Chris Anderson's words, "scale it into a corporation whose products sell at Target (NYSE: TGT)." Placement in big-box retailers would go a long way toward building the brand awareness necessary to make that billion-dollar business a reality.

It's also an opportunity for the high-end 3-D printer manufacturers. The broader the base of potential 3-D designers, the deeper the design library, and the more useful 3-D printed designs will become to the average person. You may not want to go through the learning curve for 3-D design programs, but as a design community grows, you'll become more able to find just what you want. This ties in to both my 3-D design marketplace concept, and my distributed on-demand manufacturing musings. Wired agrees:

Once you have a design on your computer, you can prototype a single copy on your desktop fabricator -- or upload it to a commercial manufacturing service and generate thousands. Essentially, you "print local" on your MakerBot and "print global" with cloud manufacturing services ranging from Shapeways and Ponoko to Chinese mass-production facilities found through …. The services will even ship the finished goods directly to customers.

If MakerBot is a threat and an opportunity to established players, Formlabs is a heat-seeking cruise missile, aimed at MakerBot, 3D Systems, Stratasys, and everyone else in the industry. In six days, the brand-new MIT spinoff has raised an incredible $1.3 million on Kickstarter from more than 900 backers, with most contributing up the minimum $2,300 that grants them first access to the Form 1 when production begins. In comparison, MakerBot's sold 13,000 printers since 2009.

To understand why, you need to understand something about the differing technologies behind 3-D printing. MakerBot printers, as well as the Cube and every other home device, use a method pioneered by Stratasys known as fused deposition modeling to melt plastic through a tiny nozzle, gradually adding layers to a work in progress until the object's done. Low-end printers suffer from resolution issues, since their nozzles aren't tiny enough and their power isn't high enough to render objects with the smooth fidelity we expect from the things we usually buy in stores.

Now, here's what Formlabs offers by comparison:

Source: Form 1.

This is the difference between fused deposition modeling and stereolithography, a technology pioneered by 3D Systems that builds solid objects from a vat of liquid by curing it with lasers. If the Form 1 succeeds, it will be the first "low-cost" stereolithography printer available, as most models can cost more than $100,000. With enough hardware and software development, this method could be the one that makes in-home 3-D printing truly viable.

Foolish final thoughts
This is an industry with a lot of action just beneath the surface. Home users are still of the hobbyist bent, but that could change as a commercial-scale design and fabrication infrastructure begins to take shape. My greatest reservation remains over the actual usefulness of a 3-D printer in most homes -- try to think about what you might need around the house that would be best acquired by printing it out, rather than ordering it on Amazon or trucking over to Target.

There's undoubtedly a place in many homes for affordable 3-D printers, but these may very well be best-suited for designers and tinkerers, who would benefit tremendously from the quick feedback of a freshly printed physical model. We're still a long, long way off from the make-anything-now ideal of a Star Trek replicator. It may arrive in this century, but I believe that the combination of a strong, diverse design community and a network of on-demand print centers is a more easily achievable goal for the next few years. Invest in that possibility, but don't forget about the future. It sometimes arrives faster than you think.

For more Foolish analysis and insights into 3-D printing, check out the Fool's most popular free report: "The Future Is Made in America." Investors of all temperaments can benefit from our analysts' review of the present and future of this exciting technology. Click here for your free information now.

Fool contributor Alex Planes holds no financial position in any company mentioned here. Add him on Google+ or follow him on Twitter, @TMFBiggles, for more news and insights.

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