This image looks a little odd, I took the picture upside down, so I flipped it. You need about 1 2/3 yards of fabric.

The dimensions of the main piece are about 19" x 17". The upper straps are about 30" and the bottom straps are about 60". I make 3 straps that are each 60" long, then I cut one in half.

The image above was my very first attempt, so the straps are too narrow and have no padding. I definitely need the padding.

I make the straps about 3 1/2" wide (finished width, I cut them about 5" wide so I can press them under and topstitch) and pad the shoulder area with folded polyester fleece.

The construction is pretty simple. Once the straps are pressed under, folded over and topstitched, I press under the main pieces, then slip the straps into position and topstitch all around (reinforcing the strap seams).