Lightweighting is an extremely important processing category in the manufacturing industry, aiming to improve product performance, fuel efficiency, reduce environmental impact, and cut costs. Its demand is growing in a wide range of fields such as automotive, aerospace, electronics, and medical devices. The main approaches include material substitution and structural optimization. In material substitution, there is a growing shift towards lightweight, high-performance materials such as high-strength steel, aluminum alloys, magnesium alloys, titanium alloys, and CFRP (Carbon Fiber Reinforced Plastics). In structural optimization, approaches from the design stage are essential, including shape creation through topology optimization, hollow structures and thinning, integrated molding, and the adoption of lattice structures. As for processing methods, integrated molding of complex shapes using additive manufacturing (3D printing), precision casting, forging, and advancements in dissimilar material joining technology are significantly contributing to lightweighting. By comprehensively utilizing these technologies, we aim to realize high-performance and lightweight products.