When you need a sample part or product, prototype machining is an excellent method for producing anything from a single, one-off part to a family of parts designed for a working assembly.
Using the actual material (aluminum, steel, brass, plastics, etc.) and production method for your prototype will give you the best representation of how the part will ultimately function. That is why we do recommend prototyping on a CNC milling machine or lathe and why we don’t offer 3D printing services. (Many of the concepts we see need to be made in the actual material to determine whether they will ultimately work or not.)