Here's what I did on the driver's seat back. $2 of mesh fabric (yellow, my wife's favorit color), $2 of elastic, $2 for thread, and a couple of hours at the sewing machine...
Now smaller items won't fall out, and I only spent 6 bucks. I still have leftover fabric, too, so I might make a cargo net now.

Now smaller items won't fall out, and I only spent 6 bucks. I still have leftover fabric, too, so I might make a cargo net now.