In Chap. 2, the dry blend preparation processes, the properties of these dry blends, and the various melt-compounding techniques used in the field to process rigid PVC formulations were discussed in some detail. The quality of the finished product, however, depends not only on the polymer preparation aspect but also on the efficiency of the melt processing and shaping tools, such as extrusion dies, injection molds, and blow molds. Especially critical is the need to understand and be able to relate PVC melt flow pressure and temperature and deformation properties to optimum screw, die, and mold design.