The second wall portion 26 of the pocket sidewall 20 includes a rigidifying materiel 28 (e.g., cardstock, plastic sheet, or other sturdy material) disposed between a soft material 30 (e.g., felt, cotton, and so on) that defines a inner surface of the second portion and a protective material 32 (e.g., vinyl, leather, and so on) that defines an outer surface of the second portion.