A vehicle structural member, such as a rocker panel, including a micro-truss core. The structural member includes specially configured and opposing outer panels that are welded together to define a channel therein, where the micro-truss core is placed in one of the panels or is fabricated to one of the panels during the micro-truss fabrication process before the panels are secured together. The micro-truss core can include separate individual sections, where each section has a tailored stiffness for that location in the member, or the micro-truss core can be a continuous core, where different sections along the length of the core are fabricated with different stiffnesses.