Copyright includes all rights to make derivative works.
Your instructor may be a rockin' designer, but should check out law school before giving advice like that which could get students in trouble. Whether the copyright-holder cares enough to pursue you, they definitely would have the legal right to do so and statutory damages on that can be grisly, even if you have made no money whatsoever off of your derivative work.
It is more fun to make your own stuff anyway.
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