A method of making a self-sealing membrane for a prosthetic implant includes applying tension to a first layer of a cured elastomeric material to stretch the first layer, and while the first layer remains stretched, applying a second layer of an uncured elastomeric material over a first major surface of the first layer. After the second layer is cured, the tension on the first layer is released, whereupon the first layer returns to a non-stretched configuration for holding the second layer in contraction. The method includes, while the first layer remains stretched, applying a third layer of an uncured elastomeric material over a second major surface of the first layer. After curing the second and third layers, tension is released from the first layer, which returns to the non-stretched configuration for holding the second and third layers in contraction.