Combining recycling of paper wastes (WPs) with extrusion‐based additive manufacturing represents a sustainable route to cellular cellulose composites tailored for lightweight construction. Particularly, shear mixing of shredded WPs with an aqueous solution of a polymer binder like polyvinyl alcohol (PVA) yields aqueous pastes suitable for 3D printing. As a shear thinning additive, both WP and microfibrillated cellulose account for enhanced shear thinning and dimensional stability. Opposite to the formation of dense WP/PVA composites by melt extrusion, 3D printing of aqueous pastes produces cellular cellulose/PVA composites exhibiting hierarchical pore architectures. In spite of low densities around 0.8 g cm−3, high Young’s…