The PP3DP plastic extrusion printer at MakersFactory gets the job done. Photo by Chip Scheuer.

When describing the actual 3D printing process, a good analogy to use is that of an inkjet printer, which takes information and prints it onto paper, in two dimensions, line by line, from the top down. In a similar fashion, 3D printers take information and print it, in three dimensions, layer by layer, from the bottom up.

In the past, manufacturing has largely employed a subtractive process, meaning that you start with something and cut away at it—with tools such as lathes—to get an end product. 3D printing is an additive process, meaning that you start with nothing and build something.

The limitations of subtractive machining, including the need for a trained machinist, fall away with 3D printing. Things that are difficult or impossible to machine in one piece using a subtractive process, such as complex geometric shapes, cylinders within cylinders or curved holes in a metal block, can all be done with 3D printing.

For hobbyists, 3D printers including the MakerBot Thing-O-Matic and the UP! printer work by heating and printing inexpensive materials such as plastics (including bioplastics) and chocolate (yes, friends, we are printing chocolate). Printers in this range can be picked up for under $2,000. But the price is dropping fast.

Recent Kickstarter campaigns have booted the Printrbot and MakiBot printers from prototype to market, and they both come in under $500. Like inkjet printers, the price on 3D printers will presumably drop until they hit a point that makes them standard computer peripherals.

“These technologies are like the early days of computers or laser printers,” says The MakersFactory’s Chris Yonge. “At the generally affordable level, they’re still rather crude but at the same time they’re very flexible, and they offer a huge amount of promise for the next generation.”

In addition to MakerBots, the MakersFactory has powder printers, which are the next step up the 3D printing ladder. They print using a variety of powdered materials including gypsum, nylon, clay—even glass, steel and titanium.

Using this technique, the object is printed within densely-packed layers of powder. Wherever the design designates the object, the printer puts the powdered material and a binding agent; where the design designates empty space, the printer prints non-binding, space-holding powder that is later blown away. With this self-supporting method, designs can have a level of fragility and detail that plastic printers such as the Thing-O-Matic can’t support.

On the industrial level, 3D printers can build remarkably complex things using the same additive, layer-by-layer process. Last year the Airbike, a customizable bicycle printed out of a powdered nylon that rivals steel or aluminum in strength, was unveiled by the European Aerospace and Defence group, and this year GE is rolling out a jet engine built with some 3D printed parts, including the fuel injector.

In addition to being an exciting technological advance, 3D printing is potentially less expensive than traditional manufacturing (the price of 3D printed objects ranges from a few dollars on up), it is a low- or no-waste process, it allows for unlimited customization and it will soon be widely available.

“What I find the most exciting is just the potential, the unknown,” says Mike Catterlin of TechShop San Jose. “It really does seem to have limitless possibilities.

“The technology is exciting and it’s fun to see it print stuff, but just thinking about the bigger picture of what it means and how far it can go—that’s what’s the most exciting to me.”