This is a very easy pattern to make. Its mostly dc, but I put it as an intermediate pattern because of a bit of sewing. I wouldnt recommend using this as the only protection for your cards when traveling but its a nice way of storing your cards at home You could also use this as a small bag for items like keys, pencils, phones (some big ones might not fit bit you can adjust sizes of the bag),

The bag is around 18.5cm wide and 9cm tall when folded closed. It fits a full deck of standard tarot size cards (12cm x 7cm), while still having a bit of space on the sides.

You would need a 4mm hook and yarn in a size that matches it. you could use multiple thinner yarns together though, but they should still use a 4mm hook when combined. The example on the cover is made with a very thin color changing yarn and a white yarn.