Leonardo da Vinci designed a rolling mill to flatten metal into sheets.
His drawings show rollers that press and reduce the thickness of metal as it passes between them. The concept applied mechanical power and controlled pressure to a task that had traditionally required repeated hammering.
Rolling mills became important in later metalworking because they could produce more uniform sheets and strips. Leonardo’s design belongs to his studies of machines for manufacturing, where he examined gears, shafts, rollers, and ways to transmit force.
Leonardo did not establish the modern industrial rolling mill, which developed through later advances in metallurgy and powered machinery. His drawing is nevertheless an early example of recognizing that continuous roller pressure could replace some manual forging work.