In Reply to: pvc sheats posted by stephen oranellas on 10/21/02 at 10:37 PM:
PVC sheet extrusion is very common. However, those thicknesses are not. The problem is that extrusion is a heat transfer process - heat is removed from the melt (by the die), and the melt solidifies. At 1/4" thickness, the process becomes very slow. At 1/2", it is even worse.
I suggest you go to a good search engine and search for PVC SHEET EXTRUSION. I know a number of extruders, but they specialize in engineering resins, not pvc.
For search engines, I like www.dogpile.com.