In the spirit of American Movie and Raiders!: The Story of the Greatest Fan Film Ever Made, Sam & Mattie Make a Zombie Movie is a fun movie about the indie filmmaking process.  This time, audiences watch aspiring filmmakers Sam Suchmann and Mattie Zufelt, best friends since hitting it off at the Special Olympics as youngsters, as they attempt to cut their teeth making the most outrageous party-horror ever made.  Their dream project is titled…