In many industrial fields, structural materials play a key role in the increase of performance, but new requirements in terms of energy saving, safety, materials economy… lead to more stringent requirements on materials properties. The two usual strategies –microstructure optimisation and shape optimisation-, which act at two different scales, the micrometer scale and above the centimetre scale, become less and less efficient with this new strong demand for multi-functional properties. The largely unexplored millimetre scale, domain of the so called “structural materials”, is a possible answer. Structural materials benefit of an extra degree of freedom well suited for multi-functionality: they allow using combination of materials from different classes, allow geometrical optimisation, and can be naturally integrated in structures such as sandwiches and various stiffened plate geometries. The price to pay for this extra-richness is the extraordinary wide variety of potential solutions to investigate for a given problem. Hence modelling plays a crucial role for selecting and optimising such innovative materials. This paper is an overview of a project, named MAPO (“Materiaux Poreux”), aiming at designing high-temperature materials with acoustical and structural properties.