can be employed to fine-tune the feature sizes (and corresponding aspect ratio) in the structuring of photoresists. This proves polarization to be a variable parameter next to laser power (intensity), scanning speed (exposure duration), accumulated dose, etc. Recently it was shown that combining ultrafast laser 3D nanolithography followed by thermal treatment one can achieve additive-manufacturing of 3D glass-ceramics. In addition, a plant-derived renewable pure bioresins without additional photosensitization can be employed for the optical rapid prototyping. Materials for multiphoton polymerization The materials employed in multiphoton lithography are those normally used in conventional photolithography techniques. They can be found in liquid-viscous, gel or solid state, in relation to the fabrication need. Liquid resists imply more complex sample fixing processes, during the fabrication step, while the preparation of the resins themselves may be easier and faster. In contrast, solid resists can be handled in an easier way, but they require complex and time-consuming processes. The photopolymers always include a prepolymer (the monomer) and, considering the final application, a photoinitiator, as a catalyzer for the polymerization reaction. In addition, we can find such polymerization inhibitors (useful to stabilize resins both reducing the obtained voxel), solvents (which may simplify casting procedures), thickens (so called "fillers") and other additives (as pigments and so on) which aim to functionalize the photopolymer. Acrylates The acrylates are the most diffused resin components. They can be found in many traditional photolithography processes which imply a radical reaction. They are largely diffused and commercially available in a wide range of products, having different properties and composition. The main advantages of this kind of resists are found in the excellent mechanical properties and in a reduced shrinkage capacity. Finally the polymerization steps are faster than other kind of photopolymers. Acrylic hybrid organic/inorganic resists are largely diffused due to their biocompatible and structural behavior, the most famous ones are the ceramic based OMOCERs material family and the silicon-ceramic based SZ2080. The latter, has encountered a wide use in the biological and photonic field, thanks to the tunable optical capability (such as the refractive index), just by changing the inorganic phase ratio. Epoxy resins These are the most employed resins into the MEMS and microfluidic fields. They exploit cationic polymerization. One of the best known epoxy resin is SU-8, which allows thin film deposition (up to 500 µm) and polymerization of structures with a high aspect ratio. We can find many others epoxy