3D printing has gone from a very expensive specialist technique to something that anyone (at least anyone with reasonable computer skills) can do for a starting price of a couple of hundred dollars (for example, the MakiBOX A6 LT is priced at just $200).
At present low cost 3D printing is limited to thermoplastics and other meltable materials such as candy (see The CandyFab Project by Evil Mad Scientist Laboratories) but more sophisticated machines, with considerably higher price tags than the consumer systems, can print ceramics and metals (if you can't afford one of these top end machines then companies such as Shapeways or Kraftwurx provide online services where you can upload your design and have a completed project delivered to you).
So what do people use 3D printing for? Anything and everything from toys, jewelry, and art pieces to replacement parts that manufacturers no longer supply to guns (for example, the Liberator ... as of writing the site was down "for maintenance" but there's lots of information about the design online).
The RepRap 3D printer
What's interesting is that the economics of consumer machines have been assessed and found to have real value. A recent research paper, Life-Cycle Economic Analysis of Distributed Manufacturing with Open-Source 3-D Printers by Joshua Pearce explains:
This study reports on the life-cycle economic analysis (LCEA) of RepRap technology for an average U.S. household. A new low-cost RepRap is described and the costs of materials and time to construct it are quantified. The economic costs of a selection of twenty open-source printable designs (representing less than 0.04% of those available), are typical of products that a household might purchase, are quantified for print time, energy, and filament consumption and compared to low and high Internet market prices for similar products without shipping costs.
The RepRap was the first consumer grade, open source 3D printer and having evolved through several generations the current version can be purchased for around $800. Pearce's research paper concludes:
The results show that even making the extremely conservative assumption that the household would only use the printer to make the selected twenty products a year the avoided purchase cost savings would range from about $300 to $2000/year. Assuming the 25 hours of necessary printing for the selected products is evenly distributed throughout the year these savings provide a simple payback time for the RepRap in 4 months to 2 years and provide an ROI between >200% and >40%.
Impressive to say the least and there's no doubt that the consumer 3D printing market is going to explode in the next few years and evolve very quickly. But as much as printing replacement parts and customized objects sounds great, I'm even more intrigued by printing food products. As Candyfab notes:
The Revolution will be Caramelized
Finally, technology that can truly be described as "delicious."