I used the Bucket Bag method of construction for this beautiful bag (video below) but I increased the size and made the base rectangular instead of oval. I used cork fabric for the base. More details HERE
The following dimensions will make a 13 1/2 inch square bag with a depth of about 3-4 inches: Cut the outer panels, 14" high by 17" wide. Cut the base 13" by 3 1/2".
(If you want a shorter bag that is deeper, cut the base 12" by 4 1/2")
The lining pieces are 2( 2 1/2" by 17") and 2( 12" by 17")
I used an 18 inch purse zipper.
Be sure to use fusible foam or a stiff stabilizer in the tabs (rather than batting). I used fusible foam in the strap too.
This video shows the way to construct the bag:
The way I created these strips of curves is:
I used strips that were about 3 1/2 inches in width and with my rotary cutter, cut one edge free hand. You have to make the curves very subtle, if they are too extreme, you won't be able to fold over the edge a 1/4 inch (which is the next step). Finally, you top stitch the folded edge to achieve this nice, overlapping effect.
This video shows how: