The typical 3D-printing process is based on inkjet printing: A layer of resin or polymers is precisely placed onto a substrate, while the deposited layer is turning itself—by hardening—into the substrate for the next layer. Also, metal or ceramic pigments or nanoparticles (or precursor compounds thereof) are spread out on a build platform and then reacted, melted, alloyed or sintered together; for example, by laser treatment.
A lot of excitement about 3D printing derives from envisioning all the possibilities people will get to digitally design and make their own toys and goods .
The term additive manufacturing contrasts the term subtractive manufacturing, which refers to the traditional machining and manufacturing processes including cutting, sawing, fracturing, cleaving, carving, drilling, polishing and finishing off. Instead of shaping a product by starting with a material piece or block and generating dust and waste, the 3D approach structures a product by building lightweight architectures from optimized resource minima.
Keywords: engineering, chemistry, nanotechnology, advanced materials, design, fabrication, mass production.
References and more to explore
 Larry Greenemeier: To Print the Impossible. Scientific American May 2013, 308 (5), pp. 44-47.
 Larry Greenemeier: Scientists Use 3-D Printer to Speed Human Embryonic Stem Cell Research [blogs.scientificamerican.com/observations/2013/02/04/scientists-use-3-d-printer-to-speed-human-embryonic-stem-cell-research/].
 The Economist: The printed world [www.economist.com/node/18114221?story_id=18114221]