yes, I used four pieces, two front and back. I used spray adhesive and fabric to cover it and then solvent based contact adhesive to glue the fabric covered cards together. An elastic hairband holds the ipad in and another one holds it closed when not in use.
actually, I take it back, I used cereal box for the outer and folder card for the inner. So two pieces of cut up ring binder for the inner front and back covers and cereal box for the outside of the front and back cover.
You could use the plastic that's sold for making bag bottoms if you wanted extra stiffening. I found that a couple of layers of interfacing were fine, especially the still stuff that feels like thick paper. There's a tutorial here which was quite good apart from getting the corners properly sharp which I found a bit difficult: whipstitchfabrics.com/blog/kindle-cover-tutorial/