Abstract: A milling tool for machining clay in the formation of clay models comprising a cutting portion with a sharp point adapted to be guided over the surface of a clay block to produce characteristic lines at a predetermined depth prior to removal of excess clay at depths substantially equal to or less than the penetration of the tool wherein provision is made during the cutting operation for removal of clay chips to produce a clean continuous groove that results in a precise, continuous character line on the clay model following removal of the excess clay.