A method of manufacturing a bladder element (10; 110; 210) comprising: forming at least one of a first polymeric sheet (20; 120; 220), a second polymeric sheet (22; 122; 222), or a third polymeric sheet (24; 124; 224) with a contoured surface profile (P; P10; P14); and after said forming, stacking the first polymeric sheet (20; 120; 220), the second polymeric sheet (22; 122; 222), and the third polymeric sheet (24; 124; 224) in a mold assembly so that the second polymeric sheet (22; 122; 222) is between the first polymeric sheet (20; 120; 220) and the third polymeric sheet (24; 124; 224); characterized by applying fluid pressure in the mold assembly: between the second polymeric sheet (22; 122; 222) and the third polymeric sheet (24; 124; 224), forcing a first surface of the second polymeric sheet (22; 122; 222) into contact with an inner surface of the first polymeric sheet (20; 120; 220), or between the first polymeric sheet (20; 120; 220) and the second polymeric sheet (22; 122; 222), forcing a second surface of the second polymeric sheet (22; 122; 222) into contact with an inner surface of the third polymeric sheet (24; 124; 224), or between the first polymeric sheet (20; 120; 220) and the second polymeric sheet (22; 122; 222), and between the second polymeric sheet (22; 122; 222) and the third polymeric sheet (24; 124; 224), forcing both the second surface of the second polymeric sheet (22; 122; 222) into contact with the inner surface of the third polymeric sheet (24; 124; 224), and the first surface of the second polymeric sheet (22; 122; 222) into contact with the inner surface of the first polymeric sheet (20; 120; 220). forming at least one of a first polymeric sheet (20; 120; 220), a second polymeric sheet (22; 122; 222), or a third polymeric sheet (24; 124; 224) with a contoured surface profile (P; P10; P14); and after said forming, stacking the first polymeric sheet (20; 120; 220), the second polymeric sheet (22; 122; 222), and the third polymeric sheet (24; 124; 224) in a mold assembly so that the second polymeric sheet (22; 122; 222) is between the first polymeric sheet (20; 120; 220) and the third polymeric sheet (24; 124; 224); characterized by applying fluid pressure in the mold assembly: between the second polymeric sheet (22; 122; 222) and the third polymeric sheet (24; 124; 224), forcing a first surface of the second polymeric sheet (22; 122; 222) into contact with an inner surface of the first polymeric sheet (20; 120; 220), or between the first polymeric sheet (20; 120; 220) and the second polymeric sheet (22; 122; 222), forcing a second surface of the second polymeric sheet (22; 122; 222) into contact with an inner surface of the third polymeric sheet (24; 124; 224), or between the first polymeric sheet (20; 120; 220) and the second polymeric sheet (22; 122; 222), and between the second polymeric sheet (22; 122; 222) and the third polymeric sheet (24; 124; 224), forcing both the second surface of the second polymeric sheet (22; 122; 222) into contact with the inner surface of the third polymeric sheet (24; 124; 224), and the first surface of the second polymeric sheet (22; 122; 222) into contact with the inner surface of the first polymeric sheet (20; 120; 220). between the second polymeric sheet (22; 122; 222) and the third polymeric sheet (24; 124; 224), forcing a first surface of the second polymeric sheet (22; 122; 222) into contact with an inner surface of the first polymeric sheet (20; 120; 220), or between the first polymeric sheet (20; 120; 220) and the second polymeric sheet (22; 122; 222), forcing a second surface of the second polymeric sheet (22; 122; 222) into contact with an inner surface of the third polymeric sheet (24; 124; 224), or between the first polymeric sheet (20; 120; 220) and the second polymeric sheet (22; 122; 222), and between the second polymeric sheet (22; 122; 222) and the third polymeric sheet (24; 124; 224), forcing both the second surface of the second polymeric sheet (22; 122; 222) into contact with the inner surface of the third polymeric sheet (24; 124; 224), and the first surface of the second polymeric sheet (22; 122; 222) into contact with the inner surface of the first polymeric sheet (20; 120; 220).