You can sew two long pieces of vinyl together 20 times, and it will come out different all 20 times. There's no way to predict what will happen. Stretching one side or the other is what caused his original problem.
The vinyl was a scrap from another job, and I don't remember what it is. It is nice looking, isn't it? I'll see if I can figure out where I used it tomorrow. I think it was used in a 46 Ford I did about 1 1/2 years ago.
No one lives forever, the trick is creating something that will.