3D Printing Step-by-Step
"3D printing is usually talked about as a “magical” technology. You design something in CAD, hit print, and out comes a fully formed object a few minutes later. In reality the 3D printing process requires a lot of manul labor. A tremendous amount of pre-preparation and post processing are required to make a quality printed piece. The gameblog Neoseeker has a great video which shows the 3D printing process in depth, from beginning to end, including all the drudge work.
The video demonstrates the production process used by a company called FigurePrints that turns video game characters into sculptures using a ZCorp 3D printer. Each 3D printer utilizes a slightly different process, but most of the steps in this overview carry over to printers made by other companies." (http://replicatorinc.com/blog/2009/01/3d-printing-step-by-step/)
See also CNC Milling Process Videos