Just reviving this thread in case anyone is taking on the DIY plastics challenge since times have changed...
I found a great source for lasercut, polished edge plastic to be made for you, low cost, no minimums, in any shape you need. They can work from sending in the originals, or from a drawing by email. I think he uses plastic in-between 1/16 and 1/18 that measures roughly .093" thick plastic. It's very nice stuff. And with the new water-slide papers so inexpensive to buy on Amazon these days, I think this whole process to make your own plastic has become pretty easy.
Contact David at www.upkickpinball.com and [email protected]