While in theory you can get a manufacturer to grant you rights before you tell them the idea, they almost never agree to signing anything like that, because that would rule out possibilities for them if for some reason they had the same idea.
It's much better to build a business of your own than try to sell an idea to enhance somebody else's business.
ps: for background, I have a multimedia presentation about the problem of ideas on my website at timberry.com
Tim Berry is the chairman of Eugene, Ore.-Palo Alto Software, which produces business-planning software. He founded Bplans.com and wrote The Plan-As-You-Go Business Plan, published by Entrepreneur Press. Berry is also a co-founder of HavePresence.com, a leader in a local angel-investment group and a judge of international business-plan competitions.