Nuhill Technologies provides services for product design and development, primarily in the areas of prototype fabrication and computer-aided design. At Nuhill, most of their work involves injection molded plastic components, in both design and prototyping. They also work in castings, CNC machining, blow molding, and other fabrication methods. Nuhill has been in business since 1992 and their management team has been involved in design and prototyping since the mid-70s. While they are an established, trusted shop, they also keep up with the latest developments in the field. Recent additions to the Nuhill team include college graduates who specialized in industrial technology and model fabrication. In theory, the Stereo Lithography Process (SLA) is deceptively simple: photosensitive liquid plastic is hardened when a bright light strikes it. By controlling the location of the light beam only portions of the liquid plastic are hardened. By hardening one layer at a time on the surface of a vat of liquid plastic, a part is built vertically layer by layer. In practice, the technology underlying this process is quite sophisticated. The photosensitive liquid plastic that is used in the SLA process is a resin that has been developed specifically for the rapid prototyping industry. The light source is a specialized ultraviolet laser with a beam diameter of less than .020" [.5 mm]. The mechanisms that control the position of the laser beam and the hardening resin are accurate and repeatable to very tight tolerances. When all the tolerances of the laser, the resin and the machine are put together, parts are routinely fabricated with a tolerance of better than +/- .005" [.13 mm]. At Nuhill Technologies, they use the SLA3500 rapid prototyping machine built by 3D systems to create the models required by their customers Computer software is required to create the original virtual models of the parts to be prototyped. This is usually done with solid modeling computer aided design software. While there are other model data formats that can create STL files, solid model CAD files are the most common. Examples of other file types include VRML, OBJ and MRI. The model data is translated into a form of data used for stereolithography called the STL format. The STL format is a collection of flat, triangular facets that closely approximates the original model. STL formatted files are the input data for the SLA process