When I travel internationally, I feel like I have so many things to keep track of like my passport, plane tickets, maps, credits cards/cash, ID cards, and so on. My wallet isn't really the perfect size or shape for all of these items, so I made myself a simple passport book for my many checkpoints through Asia.
My materials included a cheap hard cover notebook, grey vinyl, a heavy-duty sewing needle, scrap fabric (for the pockets), and later on I added in a binder clip.
First, I dissected the notebook and pulled out all the paper while maintaining the binding in the center. With the book open, I measured it's perimeter and cut out a piece of vinyl to those dimensions with a bit of wiggle room. I then measured the dimensions of one cover side and cut that out twice (with wiggle room again). I wanted to hold my passport on the right side, so I cut a slit up and down just a bit longer than my passport binding. On the left side, I wanted to hold cards, so I cut multiple strips on top of each other a bit longer than a credit card. To keep the cards in place, I measured a long piece of scrap cloth just wider than a card and as long as the number of cards I wanted to hold * 1.5 (it was really a lot of eye-balling, so you might have to test this out a bit on your own).