All Prototype Company’s and/or Machine shops today will require a 3D graphic drawing, to even quote a job.
Mechanical prototypes must be a wireframe drawing, some machines can use solid surface 3D graphic, example: CNC Lathe.
What does matter is the type of file they can use. The DXF or IGES files are the most common, but others can be used too. (Acad, Ge3, ect.)
Having only #1 prototype made will be quite expensive. Usually the more you order the less they cost. This is due to the fact that each machine requires a set up time, and in most cases this can take up to an hour or less.
The best way to start is by trying to create one yourself, it does not have to be made out of the material you really want, but made out of a mockup material. This can be made from wax, clay or wood. The Auto industry always creates there new designs in clay first so they can make changes in the looks and/or functionality.
Once you have your mockup created, you may want to have copies made. Spin casting is the best way to create multiple copies of a soft metal alloy product. Milling is the fastest way to create multiple copies of steel, Stainless steel, Brass. Ect. You get a clean finish and stable dimensional product; you can have your item finished in different ways.
• Silk Screening
• Metal Brushing
• Surface Grinding
• Buff Polishing
• Bead Blasting
• Vibratory Finishing
• Powder Coating
• Black Oxide
Make sure your prototype works, fits, and is functional as you want. Then you can go on to all the other parts of selling you idea to the big companies.