The human form captured in a shape
The shoe last is one of the most important items in shoe development. It is a representation form of the human foot but also takes in consideration the type of shoes being made.
Thus a last can have different attributes like the heel high or the toe shape. Different construction techniques (basically how the upper is attached to the sole) require different types of last.
The ergonomics, fit and style of the shoes are determined by the last used on its design. In the past lasts were traditionally made of hardwood or cast iron but today's material of choice is high-density plastics which can endure the heavy machinery process in the factories and are recyclable.
Modern lasts are designed in computers using a CAD (computer-aided design) software. However an experienced last maker can further refine the computer designed last making subtle corrections that improve the fit and comfort.
The last is not only important during the development phase. It is also used in the 'shoe lasting' operation during the mass production phase. This operation is part of the process that attaches the upper to the outsole.
The last is used to hold the upper in place, slightly stretching it, while the sole is permanently attached to it.