I have a large experience with industrial 3D printers and I know quite well how do they work. I make .STL files prepared for prototyping from ready-made 3D models using Magics software. Along with 3D printing STL-file allows you to calculate how much material will you need to manufacture the product. Also I can adjust a 3D model (or create new one) according specifics of different prototypers (divide it to pieces which have size suitable for particular 3D printer and are convenient for production and montage).