In this paper a novel approach is introduced to address manufacturing-induced size effects in braided composites. This approach involves the use of a fully parameterised representative volume element (RVE) model. To investigate the influence of structural parameters associated with thickness, such as nesting-induced undulation, roving displacements and fibre volume content, on the mechanical properties of bi-axially braided composites, a Python-based tool has been developed that combines different programs and algorithms to determine elastic stiffness parameters of the specific unit cell.