Two-Photon Polymerization enables fabrication of two and three dimensional polymer structures. For structuring, a highly cross-linking acrylate monomer is mixed with a photo-initiator. Using femtosecond IR light as an excitation source, feature sizes down to 100 nm can be achieved. Applying stimulated emission depletion (STED) reduces the feature size even further [1, 2]. Recently, our group developed functional polymer structures below the diffraction limit by mixing metal oxo clusters into the acrylate-based photoresist [3].