For generations, the dream of a metal structure light enough to float yet strong enough to endure the sea remained just out of reach — the very geometry that made such lattices light also let the ocean in. Engineers at RMIT University in Melbourne have now resolved this contradiction, weaving polyurethane foam into the hollow veins of a 3D-printed titanium lattice to create a hybrid material that floats, resists corrosion, and holds its buoyancy even when broken. It is a reminder that the most durable solutions often arrive not through brute force, but through the patient filling of empty spac