2 simple means of protection while you shop around for support:
1. Google "Non-Disclosure Agreement" write one and get it signed before you show anybody anything.
2. Document your project - daily entries in a bound book stamped/signed - whatever your - inventor's notebook, if you will.
Now, go to the library, eBay, whatever, and get some invention guides etc - From Patent to Profit is not bad - and one of the key points he brings out - You gotta have a team of players - MARKETING is not Sales - but it doesn't happen without marketing and, as you recognize -- money.
You might research possible companies that could manufacture your part(s) that fit in their product line. You would be surprised how open they might be to fresh ideas form "outside."
Better still if you have mock-ups, certainly drawings - and very importantly - some Market Analysis - Like why the thing will sell! If you decide to go it alone - a good Market Analysis and a business plan, a suit and tie - might be the ticket to a loan officer - or some other venture capital.
Your idea of having someone buy into prototype and follow-on production is not a new one - it can work - but protect yourself!
:cheers: Jim
Experience is the BEST Teacher. Is that why it usually arrives in a shower of sparks, flash of light, loud bang, a cloud of smoke, AND -- a BILL to pay? You usually get it -- just after you need it.