Smuggy: The sleeping sloth

Having just received the diaphragm motor pumps, i'm in the process of working on Smuggy's respiratory system. Although they are very lightweight and small, I'm a bit concerned about the pressure of the air being pushed into Smuggy's lung, which is a latex glove.  I'll need a material that stretches, causing a natural deflation when a release valve is opened.  However, it might be harder to inflate with the pressure values i'm currently getting from the motor. So far I have the basic circuit configured, and the main portion of Sluggy's body sewn.