We report on direct laser writing-based fabrication of optical waveguide building block components for 3D-printed photonic circuits. We used a two-photon polymerization-based process that delivers sub-micrometer resolution to manufacture waveguides that are mode matched with standard single mode optical fibers, as well as high aspect ratio adiabatic tapers and S-bends. The low loss of these crucial building block components allowed us to design and fabricate more advanced components such as waveguide Bragg gratings on which we report here as well.