And on the inside rip stop nylon was used to make it waterproof. I used pre-made bias binding to form the casing and slotted some 1/4" elastic through. This will be so much more sturdy than the very thin hat elastic used in the ones I have been buying.
It is a nice snug fit and I will "christen" it under the shower today.
Back soon and in the meantime
Happy sewing all