<p>3D-printing of concrete unlocks unique possibilities in flexural members where multiple materials and their locations can be tailored to optimize performance and cost. To fully utilize this advantage, appropriate modeling approaches are needed to design these layered sections. While analytical closed-form solutions to evaluate flexural performance are well established for homogeneous sections, extending these approaches to layered composite sections is non-trivial. This paper presents an iterative model capable of predicting the flexural load–deflection response for layered multi-material sections. The inputs required for the model are the multi-linear material constitutive relationships, which can be obtained experimentally or derived through inverse analysis of the flexural response of sections made of single materials. The model is shown to successfully replicate the load–deflection response of 3D-printed multi-material concrete beams made using layers constituted of a combination of conventional and ultra high-performance concrete (UHPC). In order to establish its robustness, the model is also validated using previously reported flexural responses of conventional reinforced concrete and hybrid (fiber and conventional reinforcement) reinforced cast and 3D-printed concretes. The model is further utilized in determining composite designs using the two chosen materials in layers that minimize the cost-and-environmental impact for a stipulated performance parameter. The proposed modeling framework thus offers a versatile tool for optimizing material distribution in 3D-printed concrete members, enabling designs that balance structural performance, material efficiency, and sustainability.</p>