It will take work to find the more creative employment situations for a mechanical engineering degree, but I believe much less work than is entailed in keeping yourself adequately employed in music or film, which are fields infamous for financial disappointment.
I searched indeed.com today for creative engineer, for musician and for movie and got 22,414 results, 2,300 results and 4,224 results, respectively. Examining a few of the creative engineer ones shows opportunities for problem-solving (which naturally engage creativity). As is pointed out at http://www.thecreativeengineer.com/, there is apt to be more than one way to solve an engineering problem.
Interestingly, http://www.census.gov/dataviz/visualizations/stem/stem-html/ reveals that at the time of a 2012 Census survey a minority of employed people in the US with engineering degrees were working as engineers.
There is a lot to be said for rigorous programs developing one’s mental competence.