McCay Tool & Engineering is a small business contract manufacturer specializing in CNC machining, CNC Turning and Fabrication for the aerospace industry.

Based in St. Louis, the company was founded in 1950 by Stanley McCay in order to fill the U.S. Government's need for contract manufacturers during the post World War II aerospace and defense retooling era.

McCay Tool quickly became known as a quality manufacturer and won a prestigious contract to produce the warhead for the Raytheon designed Patriot Missile, thereby establishing itself as one of the premier U.S. defense contract manufacturers.