Please take a look at this behind the scene video of a product design process from design through injection molding. This video shows the development of a product that we manufactured using a prototype injection mold. The video shows how the product was taken through the design and prototype phase then on to engineering, tooling and eventually production.  

This was one project that I thought we might be able to manufacture on our Fortus FDM machine but in the final evaluation of the costs we were still able to make a prototype injection mold and produce a few thousand parts for a lower cost than printing 500 pieces directly on our FDM machine. Digital manufacturing is the wave of the future.  The FDM machine that we use is very similar in technology to the FDM 3D printers that are quite common now.  However this machine is a larger more robust machine that is designed for making parts quicker, more accurate and in a higher resolution than a 3D printer.  The goal of this machine is to produce parts that can be used in manufacturing.  The parts do print very fast and the resolution is excellent but certainly not the same surface finish as an injection molded part. I thought that with the low numbers required for the job that this was an ideal candidate for digital manufacturing but in the end we were still able to make a prototype injection mold for a lower cost. I do believe that over time the cost of digital manufacturing will come down and printing a job like this will be more economical than making a prototype injection tool, but at this time the prototype injection molding process was the preferred method for production over digital printing.