The zinc cutter is a knife that the galvanizer and roof tiler use to cut sheet zinc. It consists of a steel shaft that is hook-shaped with a cutting surface at the end. It can be fixed in a wooden handle or made entirely of metal. The knife can also be adjustable. In that case it is elongated with an oblique cutting surface on the short side. It is screwed into a metal holder that sticks into a handle.
See also this tile cutter. [MOT]