Nylon 6.6 Rod is definitely the most popular engineering plastic; it has been around for years and has been given many different trade names over the years by various companies. It has become a plastic that because of it's versatility is specified, it seems, for just about everything.__There are essentially two manufacturing processes for Nylon 6.6 Rod, extruded and cast. As the names suggests, extruded is manufactured by heating the polymer and forcing it through a circular die. Whereas cast Nylon 6.6 Rod is produced by melting the polymer and pouring into metal tubes that are capped at one end open at the top.