Macchiarini returned to the United States in 1928 and, with the arrival of the Great Depression worked from 1929 to 1935 as a stone carver, with several Bay Area firms; some of which were funded by the Federal Arts Project of the Works Progress Administration (WPA). While employed as a stone carver, he worked on projects in the 1930s with such sculptors as Beniamino Bufano and Ralph Stackpole. Like Bufano, Stackpole, and many other Bay Area artists, Macchiarini was active on the political left. At a student demonstration during the 1934 West Coast waterfront strike, he was severely beaten by San Francisco police officers.