By 1958, Mouse had become fascinated by the "Weirdo Hot Rod art" movement that had begun in California a decade earlier. Having developed skills using an airbrush he began painting T-shirts at custom car shows. There he met and worked with Ed "Big Daddy" Roth, the leading exponent of Weirdo Hot Rod art. Mouse was also strongly influenced by the art of Rick Griffin, with whom he would later collaborate on posters and album covers. In 1959, Mouse and his family founded Mouse Studios, a mail-order company, which sold his products. In 1964, he was invited to help in the design of Monogram automobile model kits using the "monster" cartoon characters he had developed to compete with Roth's "Rat Fink" character.