Spike Lee and Adam Sandler both founded their own production companies.Frazer Harrison; Tommaso Boddi/Variety via Getty ImagesAfter years of working in the industry, many actors start production companies of their own.Reese Witherspoon and Nicole Kidman, for example, produce some of the titles in which they star.Plan B, formerly owned by Brad Pitt, has produced three films that won best picture at the Oscars.For some actors and directors, launch…