A last is a form in the approximate shape of a human foot, used by shoemakers

Shoemaking

Shoemaking is the process of making footwear. Originally, shoes were made one at a time by hand. Traditional handicraft shoemaking has now been largely superseded in volume of shoes produced by industrial mass production of footwear, but not necessarily in quality, attention to detail, or...

 and cordwainer

Cordwainer

A cordwainer is a shoemaker/cobbler who makes fine soft leather shoes and other luxury footwear articles. The word is derived from "cordwain", or "cordovan", the leather produced in Córdoba, Spain. The term cordwainer was used as early as 1100 in England...

s in the manufacture and repair of shoes. Lasts typically come in pairs, and throughout their history have been made from many materials, including hardwood

Hardwood

Hardwood is wood from angiosperm trees . It may also be used for those trees themselves: these are usually broad-leaved; in temperate and boreal latitudes they are mostly deciduous, but in tropics and subtropics mostly evergreen.Hardwood contrasts with softwood...

s, cast iron

Cast iron

Cast iron is derived from pig iron, and while it usually refers to gray iron, it also identifies a large group of ferrous alloys which solidify with a eutectic. The color of a fractured surface can be used to identify an alloy. White cast iron is named after its white surface when fractured, due...

, and, more recently, high density plastics.
Lasts are made to varying degrees in the shape of the human foot, depending on their specific purpose. They come in many styles and sizes, depending on the exact job they are designed for.