Apologies in advance for hijacking this thread with a solicitation, but I'm currently seeking mentorship in this exact area. If anyone has experience in starting an ETF, getting it funded, listed with exchanges and distributing it to clients I really need to pick your noggin. Email in my profile. Thanks!
You'll need a lawyer specialized in the field. Check the SEC filings for ETFs similar to the one you want to start, they have the law firm listed.
It costs a lot of money and is a slow process, usually performed by professionals with many years of experience in finance. It's almost certainly a bad idea for you to pursue the idea.