Abstract: The present invention provides materials and methods for forming an interface between an appliance and living tissue using a foamed elastomeric material which contacts the tissue or similar surfaces. The elastomeric material is in the form of a durable and washable material that, when applied to or implanted in living tissue or similar surfaces, displaces and flows in to non-conforming areas creating an air and/or water tight seal that substantially returns to an original shape when removed from the contact surface. The appliance may also include structural elements designed to optimize comfort, compliance and seal achieved through minimizing the pressure variation along the contact surface of the therapy device.