Ski areas use HDPE mostly or UHMW, some lexan or something still. All are pricey.
You can get sheets of pvc but as mentioned it's better to just buy some small tubes and put them all the way across the features. Then you have a round edge for coping and a smooth slidy surface. Also having the tubes instead of a flat piece of pvc can make it slide faster.
Can be done pretty damn cheap. Or if you really want to might be able to find a mtn getting rid of their old topsheets in the fall and snag some. But then you'll want steel coping and it's kind of a lot to get if your frame is still going to just be a wood frame with everything slapped on there.
Sometimes easy and cheap is a good option.