The car seat cover finally finished. Here is the longwinded decision process - none of which worked really. In the end a stretchy option was easier. To get an outline tuck the stretchy material into the existing seat cover, then mark with tailors chalk. Then lay out the fabric and add about a 2 inch border. Make a hem and thread through some elastic tightening to fit. I think there are probably easier ways to make holes for the straps. Buttonholes done with a sewing machine (with a stiffer fabric as backing) would work just as well.
The next thing on the finishing list
