Dilon - you've been posting your request all over the internet forums, but I don't think any of us know what a "DSLR cage" is... Will it keep my 60D from escaping into the wild? Does it keep my 5DII safe from theives while I'm in the men's room? Is it some kind of "Fig Rig" device that improves DSLR handling while shooting video? Que es????
The short answer; Get yourself a non disclosure agreement, go to a couple of different shops and show them your design. NDA is not iron clad but it shows you are concerned about your intellectual property, most manufacturers will respect that. In my experience it’s not the idea but the ability to market and distribute the product that is the biggest hurdle. Second to that is price structure vs. volume.
I have a long answer but would not want to bore everyone with that, send me an email if you want the longer answer.
Wow, thats really nice of you to help him out Steve. Personally i love the idea of more gear on the market, even if my wallet gets thinner with each new piece i see!