If you're still at the idea stage, you will want to prototype first. If it's small enough, you can print it with a MakerBot (Desktop 3D printer for $1200 or so). Alternatively, you could use ShapeWays (the "fedex/kinkos" of 3D printing). Until you actually have production volumes in the hundreds (perhaps thousands) of units, this will be the cheaper, faster, easier option.