Vibrations in metal machining is an urgent task, the solution of which allows to reduce the roughness of the machined surface and increase the durability of the tool. The article deals with the operation of face milling on extended mandrels. The tool setting has a reduced rigidity, which leads to vibrations of the mill and obtaining unacceptable surface roughness. Reducing the vibrating masses reduces the amplitude of the tool’s natural vibrations, reducing the roughness of the machined surface. The paper proposes to reduce the mass of the mill body by creating an internal honeycomb structure by the method of topological optimization when manufacturing such a tool using additive technologies.