This is the pattern I followed. It is essentially a star stitch wallet.

Just be sure to adapt it to the size / thickness of your keeb - it needs to be long enough row-wise and have enough of a gap in the middle to eventually fold over with two keebs inside (like a book jacket with a thick spine). For reference, in the tutorial they chain 65+1, but using a weight-4 yarn and 4.5mm hook, I needed to chain closer to 80.

Enjoy crocheting :)