A credit card case of paper. 10 centimetres × 7 cm.
Thick and strong paper is good. Laminated paper is better.
Cut paper and lining cloth to inside.
Draw the fold lines by scratching with an awl. Make a slit.
Fold cloth and iron it.
Fold paper and glue cloth.
Paper case is cheap and weak.
It's easy and unexpensive. You can make various cases and use always new one.
This leather case has a partition.
I used thick leather for outside, thin leather for lining.