Finding a product development company is relatively easy; check the Yellow Pages under "product development" and "marketing." You may also be able to find a product development company through referrals from family, friends and business contacts.
Don't be afraid to call a small company with a product similar to your own idea and ask to speak to the inventor. Many times, he or she will be more than happy to assist you. If the inventor didn't use a product development company, there is a good chance he or she knows of someone who has.
Product development companies are very helpful when your idea is complex. One of the primary functions of a product development company is to help you figure out how to get your product made out of suitable materials within a profitable cost structure. Also, if you are faced with many manufacturing alternatives, these companies can help you narrow the list. Of course, when deciding whether to use a product development company, you must weigh the benefits against the costs.
T-2 Design Corp., (310) 656-9922, http://members.aol.com/t2design
Sen. Joseph Lieberman, Senate Hart Office Bldg., Washington, DC 20510, http://www.senate.gov/member/ct/lieberman/general