Ask HN: Hardware startup looking for good industrial Design firms

Looking for a good industrial design firm for Proto-typing a hardware concept that has to do with 3.mm jack instalation in smartphone's. I don't see any other way in constructing this piece of hardware other then going through an industrial design firm. I want to see if its possible to construct what it is i need, it doesn't matter where they are located as long as its in the U.S. Please recommend any hardware firms if you think it will help, i'm located in the east coast.