The controlled realization of material gradients in laser powder bed fusion (PBF-LB) using AISI 316L stainless steel and H13 tool steel enables functionally graded components that combine corrosion resistance and high-temperature mechanical performance in a single part. In this work, a mathematical–geometrical inverse-design approach is proposed for the development of an add-on device for multi-material powder bed systems: starting from a prescribed spatial transition law between the two materials on the component, the corresponding shape of a powder divider in the feed chamber is determined so as to reproduce the target local volume fraction distribution of 316L/H13 on the build plane, without substantial modifications to the PBF-LB machine architecture.

The method is implemented and validated on bi-material 316L/H13 specimens manufactured by PBF-LB, comparing the theoretical transition profile with the experimentally obtained interface through metallographic analysis and hardness mapping along the gradient direction. In addition, an optical monitoring system is employed to enable real-time verification of the material transition during the process. Uniaxial tensile tests performed on specimens extracted at different positions along the gradient are used to identify which material transition law yields the most favorable combination of strength and ductility, demonstrating the feasibility and mechanical relevance of a mathematically driven design of material gradients in multi-material powder bed systems.