I've created the ultimate converter lung for cosplay. Lungs made of hard materials restrict movement and can damage the suit. For example, try bending forward and backward with a cutting board or phone book in your chest. You'll find it quite difficult to move. This is the ultimate converter lung made of urethane rubber sponge, cotton, silicone, and felt. It's quite popular locally. Please sew the edge of the lung to your suit, about 5mm in from the edge. If you can sew a dishcloth, you'll be fine. Lung size per side: approximately 41cm (length) / 23cm (width) / 5cm (thickness). Currently, it has a glossy finish, but you can make it matte by applying baby powder and wiping it off with a damp towel. If you want to see a video, please search "converter lung" on Yahoo Auctions. Current Status