coin money
To earn a very large amount of money, especially by doing something very successfully. We'll be coining money if we can manage to secure a trading partner in China. I hear Sarah been coining money with sales from her latest novel.
coin money
Also, mint money. Make a great deal of money easily or very quickly. For example, With a monopoly on the market he could coin money, or These highly motivated realtors just about enable the agency to mint money. This hyperbolic expression dates from the mid-1800s.