Why Not Hire an Artist?
If you are seeking a license the Dear Rich Staff suggests that you consider hiring an artist instead of a prototype maker. Professional CAD drawings will provide a professional appearance for your product without the expense of preparing a prototype. As for finding a prototype maker (sometimes referred to as "model maker") use search terms such as "prototype maker" and "model maker" at Google. You can learn more about prototype preparation here.
The Legal Notes
If you intend to seek proprietary rights to your product be aware (1) you have one year from the first public display to file a patent application or provisional patent application; and (2) you should enter into an agreement with your prototype maker assuring your ownership of the final prototype. You can find examples of these agreements in our book, Profit From Your Idea.