MSFC is currently pursuing the development of piezoelectric crystal oscillator strain and vibration sensors for use in structural integrity testing and monitoring. We propose to adapt these technologies to seismic frequencies of interest (~0.1 – 50 Hz). Piezoelectric sensors are not currently considered mainstream in terrestrial seismology. However, they may port well to planetary implementations where small size, low power, robustness, and high sensitivity are desirable. The current sensor prototypes use a crystal oscillator as the sensing element, measuring mechanical strain as a change in crystal impedance. We use additive manufacturing to develop a compliant structure to convert crystal impedance into an applied load on the crystal oscillator material, based on its mechanical properties.