At the beggining i have followed the messenger pattern : (Somewhat) Satchel, which i finally adapt to make a pouch for books or crochet accessories, that is why the base is the same exepted for the length, so thanks to his pattern it became this pouch. This pouch can be customised as you wish with different colors or charts, etc.
(i didn’t pay attention to any gauge)

Les instructions pour le patrons de cette sacoche sont disponibles en français sur blog (lien en dessous).

Materiels
Hook size 10
Hook size 8
50g heavy worsted yarn in main color
some heavy worsted yarn in second color (for the step 5 and 6)
Tapestry needle
2 push-buttons

Base
Step 1: With hook size 10, ch 30
Step 2: ch 1 to turn, sc in second ch from hook and each ch across
Step 3: ch 1 to turn, sc in each stitch across until the length is approximately 35 cm.
Step 4: sc in the back loop of each stitch all the way around.
Step 5 and 6: (change yarn color if wanted) With hook size 8, dc in each sc all the way around.

Forming the pouch
Step 1 : The first 1/4 of the base will be the flap, Fold in two equal part the 3/4 resting to make the pocket.
Step 2 : Along one side of the pocket, sc together both stitches of the side of the folded parts to close the pocket.
Step 3 : Do same then step 2 in the other side.
Step 4 : Sew two push-button (or magnetic button) on the flap/pocket to form an opening/closing system.

Les instructions pour le patrons de cette sacoche sont disponibles en français sur blog (lien en dessous).