An electronic device may have printed circuits to which electrical components are mounted. Plastic may be molded over a printed circuit. Vias may be formed in the printed circuit that connect metal traces on the surface of the molded plastic to metal traces on the printed circuit. The vias may be formed by drilling or by covering the metal traces on the printed circuit with mold pins in a molding tool during plastic molding operations. Plated metal traces or other metal traces may extend onto the interior surface of via holes. Vias may also be filled with conductive material such as solder or conductive adhesive. Metal members that are soldered or otherwise connected to printed circuit traces may be used in coupling surface metal traces to printed circuit traces. Antenna structure, shielding structures, and electrodes for a stylus may be formed using the metal traces on the molded plastic.