This paper proposes a design process for additively manufactured mirrors. A central support aspheric mirror and tripod support structure were manufactured via selective laser melting. To achieve substantial weight reduction, an additively manufactured body-centered cubic lattice structure was used in the mirror design. Simulation analysis showed that the mirror had good rigidity. Single-point diamond turning was applied to obtain an optical quality mirror. After assembly, the rms surface shape accuracy of the mirror was 0.069λ (λ=632.8nm). The surface roughness (Ra) of the additively manufactured metal mirror was 8.125 nm. These findings provide a strong theoretical basis and technical support for the preparation and application of lightweight metal mirrors.