By the mid-sixties Zimmerman had dropped out of the public art scene, though he continued to stay creatively active working independently and collaborating with other local artists. He was hired on as the physical facilities manager at the Louisville Free Public Library in 1966 where he worked until 1977. During his time working as physical facilities manager Zimmerman worked alongside prominent Louisville sculptor, Barney Bright to produce a set of cast aluminum door panels for the Main Branch of the Louisville Public Library at 301 York Street. The doors, which were designed by Zimmerman and sculpted by Bright, were composed of 32 panels, each baring the double “L” emblem that the library used in their seal. The doors were installed at the library’s south entrance from 1970 until their removal in 1993 when renovations were done to the York Street building.