Method and apparatus for converting, by reshaping, thin-walled nestable plastic containers into non-nestable container products wherein the nestable container is telescopically mounted on and releasably locked to a complementary male mold member, the nestable container thereafter being heated to a predetermined temperature to permit ready deformation thereof, and subsequently expanded against the non-nestable inner wall configuration of a mold cavity by differential fluid pressure to form non-nestable container products. In order to mold uniform container products by a continuous molding operation, the nestable plastic container is held in fixed relation relative to the male mold member in the vicinity of its open mouth where the container is insulated from heat.