For pure metals, typically a homogeneous distribution of material properties is assumed. This assumption reduces the complexity of the models significantly. For inhomogeneous materials like paperboard, however, this assumption is questionable. Experimental findings indicate that the structural inhomogeneity can lead to variations in mechanical properties, which in turn reduce the robustness of processes and require actions to control the product quality. In this work, we introduce an approach to modeling the local material structure in numerical simulations and investigate the material response to an uniaxial tensile test. The effect of various inhomogeneities, e.g., distribution of mass, density, and fiber orientation, on material properties was investigated, and it was found that fiber orientation has the greatest effect in most cases, while the effect of density is usually the least.