Step 3: Sew the ends together
8) Leaving a 4mm margin on the 'flap' end, sew around the three edges to the marks you made. On the other end just sew straight across the end.
9) Tip: Trim the corners off at 45 degrees, this will give sharper points once you turn it right-way-out.
10) Turn the case the right-way-out, it will look like this.