After graduation from Cal Arts, Fullmer spent roughly seven years running his own animation business producing works such as: medical, scientific and other educational films; segments for Sesame Street; television commercials; and Saturday morning television programs.
In 1987, Fullmer was hired by Walt Disney Feature Animation (now known as Walt Disney Animation Studios) for a three-month contract to animate on the "Toon Town" section of Who Framed Roger Rabbit, a job that turned into an 18-year career at The Walt Disney Studios.