This is a compact and comfortable credit card box with an adjustable capacity, so you can make it just as big as required for the cards you own.
I've been using this design since a few years already and it works pretty well for me :)
Cards are reliably kept inside the box by one rubber band plus a second one as backup.
The card stack can easily be popped out with one finger to scroll through the cards.
The body has nicely rounded edges and corners for maximum comfort when carrying it in your pocket.