Who invented 3D printing?
The first 3D printer was created by Charles W. (Chuck) Hull in the mid-1980s. It used a technique called stereolithography, in which a UV laser is shined into a vat of ultraviolet-sensitive photopolymer, tracing the object to be created on its surface. The polymer solidifies wherever the beam touches it, and the beam "prints" the object layer by layer per the instructions in the CAD/CAM (computer-aided design/computer-aided manufacturing) file it's working from. Hull founded a company called 3D Systems, which made stereolithography machines. Stereolithography is an expensive commercial technique, with machines usually costing $100,000 or more. Today 3D Systems sells 3D printers that use a variety of technologies and range from entry-level kits to advanced commercial systems, as well as providing on-demand parts services, mostly to business users.

What are the benefits of 3D printing?
3D printing gives designers the ability to quickly turn concepts into 3D models or prototypes (a.k.a., rapid prototyping), and allows for rapid design changes. It allows manufacturers to produce products on demand rather than in large runs, improving inventory management and reducing warehouse space. People in remote locations can fabricate objects that would otherwise be inaccessible to them. 3D printing can save money and material over subtractive manufacturing techniques in which material is cut, drilled, or shaved off, as very little raw material is wasted. And it promises to change the nature of manufacturing, eventually letting consumers download files for printing 3D objects—including, for example, electronics devices—in their own homes.

What can 3D printers make?
Designers use 3D printers to quickly create product models and prototypes from CAD drawings, but they're increasingly being used to make final products as well. Among the items made with 3D printers are shoe designs, furniture, wax castings for making jewelry, tools, tripods, gift and novelty items, and toys. The automotive and aviation industries use 3D printers to make parts. Artists can create sculptures, and architects can fabricate models of their projects. Archaeologists can make a 3D scan of a fragile artifact and print out a copy of the object. Likewise, paleontologists could duplicate, say, a dinosaur skeleton for display.

Physicians can use 3D printing to make prosthetics, hearing aids, artificial teeth, and bone grafts, as well as replicate models of organs, tumors, and other internal bodily structures from CT scans in preparation for surgery. Also, 3D printers are being developed that can lay down layers of cells to create artificial organs (such as a kidney http://www.ted.com/talks/anthony_atala_printing_a_human_kidney.html) and blood vessels (http://www.bbc.co.uk/news/technology-14946808) are already in the R&D phase. 3D printing can be used in forensics, for example to replicate a bullet lodged inside a victim (human or otherwise): http://www.youtube.com/watch?v=NKhpa5Nt6Ck

Printed electronics is a set of printing methods that enable electronic devices or circuitry to be printed on flexible material such as labels, fabrics, and cardboard, by application of electronic or optical inks. It provides very low-cost fabrication of low-performance devices. Printed electronics is beginning to be combined with 3D printing, allowing for the printing of layered circuitry or devices. A natural outgrowth of this potent combo is that someday you may be able to print out a future generation of gadgets from 3D plans rather than buying them.

Certain 3D printers can even be used in food preparation, to apply items in liquid or paste form such as cheese, icing, and chocolate. The French Culinary Institute has been using a Fab@Home (www.fabathome.org) open-source 3D printer developed at Cornell University to prepare artistic delicacies, and MIT has created a 3D food printer called the Cornucopia.

3D food printers could conceivably even match the Star Trek replicators, found in starship mess halls throughout the galaxy: These fictional food printers can fabricate most any food item on demand. If 3D printing lets doctors someday print a heart or kidney with internal structure, printing a steak or other foods should be a snap—though probably not cost-effective. (Maybe that's just as well, as few Earthlings could stomach a wriggling plate of gagh. http://en.memory-alpha.org/wiki/Gagh) At any rate, we're likely to see a far greater range of food products made by 3D printers at all levels of the "food chain": food manufacturers, restaurants, and home kitchens.