Fold the inside edges of what will be the opening and sew to create a finished edge. Add some decorative trim if you'd like.
With right sides together, place the 2 halves together and pin. I placed the opening sides together so they were touching but not overlapping. This creates a bit of extra at the top, but don't cut it off, you'll use it later. Sew together the 2 sides and the bottom, leave the top open.
Cut open button holes and sew on buttons. I am using clear buttons, but put black ones on here to make it easier to see. They give it a monster like effect don't you think?