You can raise capital by making a direct public offering of your shares to your customers, distributors, and other affinity groups, but start with this guide from the US Securities and Exchange Commission to ensure compliance with the law: Q&A: Small Business and the SEC. The latest change is Eliminating the Prohibition Against General Solicitation and General Advertising, which took effect in mid September, 2013.
Pros and cons are discussed in this guide to Direct Public Offering Services from Public Financial Services. (This firm also provides advice on initial public offerings and reverse mergers).
Take a Screen Test for a Direct Public Offering from Drew Field Direct Public Offerings to determine if your company is a good candidate.