The availability of the work in relationship to the demand influences the price as well. Henry Moore drove up the price of his sculpture by allowing only a fraction of his works to sell each year. The importance of the specific sculpture within the sculptor's body of work is also taken into consideration in pricing a sculpture. This work may have won a prestigious award or have been included in a major museum exhibit. You may be looking at a sculpture that culminates years of work in a series.
Some sculptors produce great quantities of sketches in pencil or ink, sometimes in color.
Others use computer technology to explore 3D models, especially useful for kinetic works. Occasionally, a full size mock-up is created. In all cases, sculptors expect surprises and challenges as the work develops at full scale. The original concept dictates the appropriate sculpture medium. A large, fluid figure conceived as an outdoor piece has to be cast, most likely in bronze.