Methods, systems, and apparatus, including medium-encoded computer program products, for designing and manufacturing rotors for disc brake systems and apparatus include, in one aspect, a method including: placing a lattice structure in a ventilation space within a 3D model to create more internal surface area within a disc brake rotor between inner and outer rotor discs; adjusting a number of lattice unit cells for the lattice structure in different regions of the 3D model between the rotor discs to increase air turbulence in the ventilation space; adjusting one or more thicknesses of beams forming the lattice structure in different regions of the 3D model between the rotor discs to prevent structural failure under predefined loading conditions; and providing an updated version of the 3D model of the disc brake rotor that incorporates the lattice structure after adjustment of the number of lattice unit cells and the beam thickness(es).