Three-D printing a gun, like printing most other things, is pretty simple. You download a digital file for a design you like. The printer reads the file, then shoots out layer upon layer of specialized plastic -- or another raw material -- through a heated nozzle in the specified shape. Not long afterward, your gun parts materialize.

The technology is roughly 30 years old, but has only recently become cheaply available and widespread. Global sales and services related to 3-D printing reached $2.2 billion in 2012, according to Wohlers Associates Inc., an increase of 28.6 percent over the previous year. The company expects that figure to increase to about $6.5 billion in 2019.

And no wonder. Consider the Urbee 2, a car being produced by Kor Ecologic using a 3-D printer. When completed, it will weigh some 1,200 pounds. Made with about 40 pieces of thermoplastic, it will be resilient, aerodynamic and mind-bogglingly efficient. Its production will require far less material than a traditional car. It will need almost no labor and take little time to assemble. Its designers can employ unorthodox shapes and materials to maximize efficiency, mold the lightweight plastic with precision to strengthen vulnerable areas, and fit most pieces together without joints or welding (although the engine and chassis will still be made of metal). In effect, they're compressing much of an automobile assembly line into a printing device.

The economic potential is stunning. Across a range of industries, R&D costs are already declining and product-development cycles are accelerating as more inventors experiment with cheap 3-D printed prototypes. The question is whether the technology will transform manufacturing more broadly.

At the moment, 3-D printing is a very small part of the economy. The printers are typically slow, and the material they use is expensive and inconsistent. As the industry advances, however, printing on demand could reduce assembly lines, shorten supply chains and largely erase the need for warehouses for many companies. Reducing shipping and eliminating the waste and pollution of traditional subtractive manufacturing could be an environmental boon.

In a few decades, things could get really interesting. Engineers should be able to blend raw materials in new ways, endow products with nanotechnology and artificial intelligence, and create objects that interact with their physical environment. Imagine military armor embedded with sensors that track wear and tear, or a turbine blade that monitors its own temperature.

The technology is already liberating entrepreneurs. As consumer-grade printers improve, a basement enthusiast will be able to make replacement parts for products he owns, invent and sell customized objects online, and potentially create new industries. As Hod Lipson and Melba Kurman write in "Fabricated: the New World of 3D Printing," the technology will be "the platypus of the manufacturing world, combining the digital precision and repeatability of a factory floor with an artisan's design freedom." In other words, the era of mass customization is quickly approaching.

David Fuller's view 3-D printers will empower creative and clever individuals in ways that we are only beginning to imagine. On the positive side, these will include artists, healthcare specialists, engineers and all sorts of inventors.

As with most new inventions, 3-D printing will also empower some sociopaths and criminals, but that is a human rather than technological problem.

In addition to empowerment, the biggest contribution of 3-D printing, I believe, concerns the efficiencies that it will create on personal, educational, corporate and governmental levels. It is part of the accelerating pace of technological innovation that Fullermoney often mentions, for which there is no creative limit.

The leading manufacturer of 3-D printers is the US company 3D Systems Corporation (DDD US) (weekly & daily). Having accelerated higher once again, it is currently overextended. It is certainly not cheap, as you can see from this Bloomberg page. However, it should have an exciting future and I would regard it as a speculative buy following a pullback to the 200-day MA.

The main beneficiaries of 3-D printing, I imagine, will be inspired inventors and successful multinational corporations (Autonomies).