Developed at the Massachusetts Institute of Technology, three dimensional printing is one of several technologies known collectively as "rapid prototyping technologies."  They allow designers very quickly to make a solid model from a three dimensional representation created on a computer.  In addition to speed, 3D printing offers tremendous flexibility in the forms and geometrical shapes that can be fabricated.  It has already had a great impact on industry by making it easy to create prototypes and models of new devices.  In the future it is likely to have an even greater impact on manufacturing, for example, through the direct fabrication of metal and electronic parts.  In addition, a wide range of other applications from medicine and dentistry to art, are being explored.

Links:
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Three Dimensional Printing Laboratory at MIT.  This is where 3D printing was invented.  The site includes sections explaining what 3D printing is, how it works, and what some of its applications are, as well as information about current research and the scientists and engineers who are doing it.

Three Dimensional Printing.  One section of a brief tutorial on rapid prototyping technologies from Castle Island Co.  The tutorial also includes sections on related technologies such as stereolithography and fused deposition modeling.

"Digital Fabrication," a history of three dimensional printing.  From Landfoam Topographics, architectural model builders.  The rest of this site includes pictures of some really neat architectural models (not necessarily constructed with 3D printing, but interesting nonetheless).

"Printing in three dimensions," by Jean Thilmany, Mechanical Engineering (May 2001).  An excellent non-technical discussion of the technology of three dimensional printing and its applications.

The Imaging Technology Group at the University of Illinois at Urbana-Champagne offers three dimensional printing to its users on its Genisys Xs 3D printer.

"Mind Into Matter:  New Digital Sculpture," by Dr. Francine Koslow Miller.  "[O]rganized in conjunction with the first Boston Cyberarts Festival, [this exhibit] explores the innovative use of the computer and rapid prototyping (RP) technologies to create three-dimensional art."  Where technology goes, art is certain to follow (and sometimes lead).  This essay explains the exhibit and has links to various artists represented. Very cool!

Rapid Prototyping (using inkjet technology, including 3D printing) from eFunda (Engineering Fundamentals - a portal site and on line publisher for engineering content and software).

Printing Teeth??  Dr.  Juan Loza, Director of Postdoctoral Prosthodontics Program at the Harvard School of Dental Medicine is using three dimensional printing techniques to fabricate dental ceramic crowns.