What metalworking machine did Leonardo da Vinci design to produce thin sheets?

Leonardo da Vinci designed a rolling mill to produce thin sheets of metal. The machine used rollers to compress and extend metal as it passed between them.

Rolling is a powerful metalworking method because repeated passes can reduce thickness more consistently than hammering alone. Leonardo’s design reflects his interest in mechanizing workshop labor and improving the control of force through gears, screws, and rotating components.

The drawing should not be confused with a blast furnace, which produces molten iron, or a wire-drawing bench, which pulls metal through a die to make wire. Industrial rolling mills later became much larger and more specialized. Leonardo’s concept is best understood as an early mechanical design related to a process that became central to modern metal production.