In this work the design, fabrication and testing of the first 3D-printed and wet metallized capacitive z-axis accelerometer with a volume of 3.4 cm × 8 mm × 2.5 mm is presented. Preliminary results well match the modelling, both in terms of electromechanical parameters and of measured sensitivity, thus validating the proposed concept and fabrication process. With a spring thickness of 300 µm and a gap size of 200 µm for capacitive read-out, the presented device and the shown results can be considered as the first step toward 3D-printed MEMS (Micro-Electro-Mechanical Systems) inertial sensors.