a person specializing in operating machine tools

a person who can take the raw materials and manufacture a finished part, either by copying an existing part or by taking the information off a drawing (blueprint)

a skilled craftsman who constructs and repairs all kinds of metal parts, tools, and machines through the use of blueprints, machine and hand tools, and precision measuring instruments

A machinist is a person who uses machine tools to make or modify parts, primarily metal parts. This is accomplished by using machine tools to cut away excess material much as a woodcarver cuts away excess wood to produce his work. In addition to metal, the parts may be made of many other kinds of materials, such as plastic or wood products.