  This article presents a new and individual way to generate opto-mechanical
components by Additive Manufacturing, embedded in an established process chain
for the fabrication of metal optics. The freedom of design offered by additive
techniques gives the opportunity to produce more lightweight parts with
improved mechanical stability. The latter is demonstrated by simulations of
several models of metal mirrors with a constant outer shape but varying mass
reduction factors. The optimized lightweight mirror exhibits $63.5 \%$ of mass
reduction and a higher stiffness compared to conventional designs, but it is
not manufacturable by cutting techniques. Utilizing Selective Laser Melting
instead, a demonstrator of the mentioned topological non-trivial design is
manufactured out of AlSi12 alloy powder. It is further shown that -- like in
case of a traditional manufactured mirror substrate -- optical quality can be
achieved by diamond turning, electroless nickel plating, and polishing
techniques, which finally results in $< 150$~nm peak-to-valley shape deviation
and a roughness of $< 1$~nm rms in a measurement area of $140 \times 110$
$\mu$m${}^2$. Negative implications from the additive manufacturing are shown
to be negligible. Further it is shown that surface form is maintained over a
two year storage period under ambient conditions.
