that much time for a complicated bag) i just cut out two big rectangles (with lee way inches to fit the blocks) and also a couple of inches for the top to make the draw string hole.
sew the sides and leave some of the top for draw string. i left about an inch and a half on top for the draw string.
fold the open top half on the wrong side and sew them.
then, i cut out an inch width of fabric about double the length of the width of the bag. cut two strips if you want to be able to pull the bag close both ways, but if not, 