Leonardo da Vinci designed a rolling mill for producing and shaping metal with rollers.
A rolling mill passes metal between rotating cylinders, reducing its thickness or producing a more uniform shape. Leonardo’s notebooks contain designs for mills in which rollers were turned by mechanical power. The concept belongs to his broader study of machines for metalworking and manufacturing.
Rolling offered an important advantage over repeatedly hammering metal by hand: it could apply pressure continuously and produce more consistent results. A controlled gap between the rollers would determine the thickness of the material. Leonardo’s drawings show his interest in coordinating shafts, gears, and adjustable machinery.
The design should not be confused with a printing press, which transfers ink to a surface, or a wire-drawing machine, which pulls metal through a die. Leonardo’s rolling-mill concept is significant as an early vision of mechanized metal production, although surviving drawings do not prove that he built a full industrial mill.