He married Anne Steele in 1925 and the couple settled in Essex Fells, New Jersey. There Marsh set up a metal forge which he used to create industrial and residential lighting fixtures. In 1948, the Marshes relocated to Pittstown, New Jersey where James continued operating a forge, expanding the operation to include decorative metal work. His work was mainly in the American Arts and Craft style.[2]
In 1964, he purchased the M. C. Mulligan & Sons Quarry, also listed on the NRHP, and donated it to the Clinton Historical Museum, now known as the Red Mill Museum Village.[4] On October 9, 1965, the James Randall Marsh Historical Park was dedicated at the museum.[5]