Additive manufacturing of electronic devices is challenging because plastics and metals, which are both required as insulator and conductor, respectively, have very distinct thermal properties. Despite significant research efforts, the currently available electronic-printing methods are still limited by low printing speeds and high manufacturing costs. In this work, a hybrid printing method is proposed that combines fused deposition modeling (FDM) with laser sintering to print thermoplastics and copper in a single process. A copper and copper-oxide composite filament is developed that is compatible with FDM printing. The composite undergoes in situ reduction under laser exposure and produces a highly conductive copper network. Using the home-developed 3D printer, 3D conductive vias embedded in thermoplastic dielectric are demonstrated. The printed copper electrodes have low resistivity of 4 × 10 −4 𝛀 cm and are compatible with soldering. This novel metal-deposition approach and setup prove a novel concept for developing modern electronics using additive manufacturing.