The integration of photonic components into opto-electronic semiconductor devices has made tremendous progress. With an increase of on-chip integration density, efficient optical off-chip interconnects are becoming indispensable for further progress. Such off-chip interconnects can be realized as 3D freeform waveguides. However, it is a big challenge to model, design, and optimize 3D freeform waveguide structures, in particular, so-called photonic wire bonds. Propagation losses of photonic wire bonds depend heavily on the shape of the structure and in particular on its curvature. Our goal is to understand how 3D curved waveguides can be designed in an optimal way that minimizes losses, to develop the necessary design tools, and to benchmark their viability by comparison with experiments.