Sponges are a general term for porous materials manufactured by foaming materials such as polyurethane, polyethylene, and rubber. They possess properties such as lightness, elasticity, water/oil absorption, thermal insulation, cushioning, and sound absorption, with their functions varying depending on their open-cell or closed-cell structure. In manufacturing, cutting processes such as die-cutting, slicing, and router processing are frequently used, primarily on sheet or block materials. Additionally, lamination by adhesion, composite formation with different materials, and thermoforming or surface treatment tailored to specific applications are also performed. Their functionality is utilized in a wide range of fields, including sealing materials for automotive parts, cushioning materials for electronic devices, medical equipment, filters, and thermal insulation/sound absorbing materials for construction.