Abstract: The emergence of micro-, nano-, and molecularly-tailored multimaterial systems, driven by breakthroughs in additive manufacturing (AM), is redefining the boundaries of material innovation. Leveraging the precision and versatility of 3D and 4D printing, AM enables unprecedented local customisation of material architectures and properties. In this talk, I will present our multidisciplinary research journey, highlighting compliance-engineered multilayers for enhanced performance, morphology-optimized composites, and surface-engineered systems for functional adaptability. I will also discuss nature-inspired materials, including nacreous composites and camouflage systems that emulate biological complexity; high-performance self-sensing systems and 4D-printed adaptive structures; multiscale and hierarchical fibre composites and electrically conductive materials with advanced functionalities; and architected metamaterials featuring 2D and 3D lattices designed for energy absorption, autonomous sensing, failure mitigation, lightweighting, reversible shape transformation, energy storage, water pollutant detection, and thermal management. We demonstrate the ability to control material behaviour at the micro- and nano-scale in 3D and 4D frameworks, which enables precise tuning of strain, stress, and functionality, paving the way for unprecedented performance and fabrication methods. By integrating scalable AM techniques with the design of nano- and micro-architected hierarchical structures, our research is driving the creation of new material classes with extraordinary properties. These paradigm-shifting advancements are poised to transform fields such as defence, energy, transportation, automotive, electronics, and aerospace, shaping the future of material science and engineering.