I have recently been playing around with sewing onto PVC plastic. (Inspired by an article in Stitch magazine, Dec 08/Jan 09.) I have used two layers with pieces of fabric between, then free motion sewing them together, technically a quilt I think, as it has three layers put together.
My sewing machine drops the feed dogs, allowing the free motion but I kept finding the free motion not so free - upon close examination, I realised that the plastic was sticking to the machine.
In comes the modern invention - teflon. (Actually, it is only relatively modern, I looked it up and it was invented in 1938. Wouldn't you know it, there is some thought that it might cause cancer!)
I had bought this handy looking thing a few years ago, when I was visiting my friend in New York and had visited the City Quilter shop and HAD to buy something - but I hadn't wanted to buy anything bulky that would take up room in my suitcase. So there it was, this thing that looked like it would be ever so useful.
This is the first time I have used it, at least three years since I got it, if not four. It is actually rather fortunate that I remembered I have it. Anyway, it worked a treat, the plastic slides around on it beautifully. So now I am happily sewing on the plastic.