Years ago, when I was going on a trip abroad, I asked my mother to make me a small bag, like a sacoche, that I could wear under my jacket to hold my passport, wallet, and smartphone without being noticeable. It has a convenient pocket on the front, making it perfect for everyday use. I believe the material is a cotton-linen blend. It doesn't shrink at all, even when washed in the washing machine. In photos 5 and 6, I've taken pictures with a 600ml plastic bottle to give you an idea of the size. Also, although I'm an amateur, I've included the dimensions in photo 7.