Triply periodic minimal surface (TPMS) structures offer high porosity combined with favorable mechanical properties, making them promising candidates for cranial implants. Through implicit modelling, parameters such as cell size and wall thickness can be a dapted to local load requirements, enabling the design of implants with bone-like stiffness. This study investigates the sensitivity of TPMS structures in cranial applications with the aim of replicating the stiffness of patient-specific bone fragments. Using finite element analyses, the influence of cell dimensioning and wall thickness on porosity and structural stiffness was systematically examined. Based on these data, respon se surface metamodels were developed to determine optimal parameter combinations for achieving bone-like stiffness while maintaining high porosity. Initial manufacturing trials using laser powder bed fusion confirmed the feasibility of producing these structures with high accuracy and geometric fidelity. The results demonstrate that TPMS-based cranial implants can be tailored to individual patient morphology, providing both structural stability and potential for reduced stress-shielding.