This thesis investigates how laser-assisted printing of multilayer copper conductive traces and vertical interconnect accesses (VIAs) enhances the miniaturization of 3D mechatronic integrated devices (MIDs). The primary objective is to improve the integration of 3D circuit carriers and address current miniaturization challenges. The state-of-the-art analysis includes a novel classification for 3D multilayer devices (MLDs) and an evaluation of different VIA printing approaches. Experimental results include the parameterization of laser sintering, cleaning, and ablation processes. Further topics are the process adaptation to 3D surfaces and the optimization of copper VIA printing. Prototypical 3D MLD circuits demonstrate enhanced design flexibility for 3D multilayer resonators, lighting devices, and high-density contact pads, achieving a 100% working ratio for conductive VIAs under optimal coating conditions and low mean VIA resistances below one ohm.