Petrella continued acting as a teen and later began to study improvisational comedy, training at Groundlings Comedy Theater in Los Angeles. In the 1990s, Petrella got a small gig as a production assistant on a puppet show. He subsequently studied the art of marionette puppetry in the Czech Republic; and while living in San Francisco, he studied film and performed puppetry independently for film and stage. Petrella's other puppeteer credits include the Teenage Mutant Ninja Turtles and Power Rangers franchises.