Leonardo da Vinci designed a rolling mill to reduce metal into thinner sheets.
A rolling mill passes metal between rotating rollers, compressing it and changing its thickness. Leonardo’s notebooks contain designs for machines that use rollers and mechanical power for metalworking. The drawings show his interest in making workshop processes more controlled and repeatable.
The principle is especially useful for producing sheet metal and other regular forms. Instead of hammering a piece repeatedly by hand, rollers apply pressure along a wider area. A powered arrangement can also improve consistency and reduce the physical effort required from workers.
Leonardo should not be credited with inventing every form of rolling mill. Earlier metalworking traditions used rollers, and later industrial mills became much larger and more specialized. His notebooks are important because they document a clear mechanical approach to rolling and connect it with the broader Renaissance development of machine-assisted manufacturing.