In 1980, Hehn graduated from Linfield College with a bachelor's degree in art. Shortly after that he married, and he and his wife moved to the Chicago area where he had a series of industrial and warehouse jobs. During this time he also took nearly all of the technical drawing and graphics classes offered at a nearby junior college. The design department of the college eventually gave him his first graphics job, where he helped produce and illustrate all sorts of college publications.
Following that, he worked for AT&T doing graphics on computers for about two years, during which time he also sold a few of his freelance illustrations in and around Chicago. After returning to Oregon, Hehn tried his hand at 3D computer animation and assisted with cell animation, prop and model making and process photography for a small animation company in Portland.
Since 1988, Hehn has been employed by McMenamins. His brother Paul was one of the company's managers, and Hehn was hired to paint a sign on a door at the Fulton Pub. Other McMenamins projects gradually followed. At first he did just decorative wall painting in the pubs, but as the company expanded, Hehn also began to design logos and labels and signs for their various locations, along with murals and illustrations.