You can download this PDF pattern from here:
The finished size is: 9" x 9" x 3.5" (23cm x 23cm x 9cm).
Leather: We advice 2.0mm (5oz) leather for main body, size 32cm x 80cm; 1mm (2.5oz) leather for inner pouch, size 71cm x 2cm x2.
Hardware: 42cm No.5 zipper x1, 31cm No.5 zipper x1, No.5 slider x2, 9mm x 4mm Chicago x7, Φ20mm square buckle x2, Φ20mm dog hook x2, Φ20mm needle buckle x1,
Tools: If you are a new leather player, try to considerate to have tool kit here: http://www.leathercraftpattern.com/leather-tools-...
Step 1: Cut All Leather Pieces From Pattern, Punch Stitching Holes
here I use 1mm leather, so I glue 2 pieces of 1mm leather together flesh side to flesh side to have 2mm leather. To doing that, you can have the front zipper pouch between 2 piece of 1mm leather.
Step 2: Sew Zipper on Zipper Hole on Gusset and Front Piece, Then Sew Tabs on Gusset.
Step 3: Fold and Glue Welt Leather, Punch Stitching Holes on Them.
Step 4: Sew Gusset, Welt and Back Piece Together
You should follow the tips on pattern carefully, to overlap the right anchor points, then you can sew this bag well. Before sewing, you should thin all edges. After sewing, open the zipper, converse flesh side outside.