Post-Forming Processes Post-Forming Processes After a product is formed and cooled, it must be removed from the surrounding sheet area.Multi-Form Plastics uses several methods to finish trim parts.Steel rule cutting dies: Often used on parts .125 thick or less and on the same trim plane.CNC machine: Used on heavier gage materials and on parts that requires complex holes, openings and uneven trim planes.Saws and Routers: Sometimes used on low tolerance articles to reduce costs.