A method of producing an article based on a physical model comprising the steps of scanning the physical model to obtain a set of scan data; converting the scan data into surface data representing surface characteristics of the model; generating instruction data from the surface data suitable for causing a computer-controlled machine tool to produce an article having surface characteristics corresponding to the surface characteristics of the model; simulating executing the generated instructions on a data processing system resulting in a set of simulated surface data representing a simulated as-machined article; and generating a representation of the updated surface data suitable for producing the article.
