[3] Beginning in 1945, Reinert began working at the Metro-Goldwyn-Mayer cartoon studio and ended up at the Army Photo Center Animation Department in New York two years later.
In 1985, he began making 21-minute specials plotting the character, starting with Cap'n O. G. Readmore's Jack in the Beanstalk.
In 1997 he served as an animation supervisor on a half-hour Peanuts special, It Was My Best Birthday Ever, Charlie Brown.
In 2008, Reinert briefly returned to animation, working on the Pebbles cereal commercials at Duck Studios for Post for two years.
He quietly quit making the advertisements in 2010 after Post got sued for plagiarizing the use of a Hulk Hogan caricature.