Abstract: This invention relates to method and apparatus for making plastic tubular preforms for assemblying bottles or other containers into individual mutli-unit packages. The bottles for an integral multi-container package are arranged in a tightly-assembled group and the tubular preform is placed around the group. The tubular preform is formed from a lengthy sheet of flexible heat-shrinkable thermoplastic material which preferably is comprised of a composite foam and film laminate with the preform having a thermal fusion seal extending in an axial direction. The preform is flat-folded with a pair of axial pleated folds in diametrically opposite sides and then double-folded centrally for use in multiple unit packaging of like containers. The preforms has a primary orientation in a circumferential direction and a secondary orientation in an axial direction making it particularly useful when fully opened for heat shrinking around a group of like containers.