This chapter introduces a simple and highly versatile design motif, termed the bq‑structure, which enables guided and controllable tuning of nonlinear stiffness characteristics. The proposed motif achieves a substantial expansion—up to 200%—in the designable range of quasi‑zero stiffness, negative stiffness, and multi‑stable responses, surpassing the capabilities of conventional materials and beam‑based designs. By avoiding trial‑and‑error methods, the bq‑structure allows reliable nonlinear property manipulation through systematic parameter design. A prototype vibration isolation unit based on this motif demonstrates ultra‑low resonant frequencies below 1 Hz at practical size and payload, along with large elastic deformation capacity and structural‑level ductility. These features make the bq‑structure a powerful and general optimization tool for applications in advanced materials design, vibration mitigation, energy storage and conversion, and robotic systems.