Piezoelectric sensors require electric poling to provide piezoelectric properties. Furthermore, for a functional sensor, electrodes need to be deposited on the sensing element, which makes manufacturing the sensor a multi-process. Multi-processing limits the sensor’s shape complexity and makes it harder to embed the piezoelectric sensing elements in various 3D-printed structures. Integrating electric poling into the fused-filament-fabrication (FFF) 3D-printing technique was already researched; however, the methods require an additional electrode-deposition process and the piezoelectric sensitivities of the fabricated films were not comparable to conventional methods. This research presents the design principles of a functional, single-process, dynamic piezoelectric sensor using the FFF technique, which includes electrode deposition and electrode poling. A PVDF filament is used to fabricate the active piezoelectric layer. An Electrifi conductive filament is used to fabricate the electrodes of the piezoelectric film and the wire-like traces connecting the electrodes to the high-voltage terminals. As a result, the sensor undergoes electrode poling in the process of 3D printing. In order to study the piezoelectric response in different directions, two different dynamic sensor designs are presented. The sensor’s response to in-plane and out-of-plane loading is measured in terms of the sensor’s sensitivity. In-plane and out-of-plane sensitivities were measured for the two presented sensor designs. The proposed design principles for the FFF of piezoelectric sensors enable the single-process manufacturing of geometrically complex sensors and offer the possibility to embed the piezoelectric sensing elements into various FFF structures without an additional process.