Have you heard of people going out to the stock exchange and buying shares of stock?
Have you heard about an IPO, which is an Initial Public Offering?
Both examples revolve around the public side of investing.
You can go public if you're a well-established company and meet the stock exchange requirements.
Guess what?
Most filmmakers do not have plans to make film projects public.
At least not yet.
What you are considering instead is raising money from a few accredited investors for a private offering.
Check out the Securities and Exchange website for more information.