made of money
Very rich, as in Afford a limousine? Do you think I'm made of money? This hyperbolic expression uses made of in the sense of “composed of,” a usage dating from about 1200.
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.