A method of forming a plurality of individual induction heat-seal liners (10; 210) comprising: a) providing top (20; 220), intermediate (40; 240) and bottom (30; 230) sheets for forming top (20; 220), intermediate (40; 240) and bottom (30; 230) layers respectively of a plurality of individual induction heat-seal liners (10; 210); b) laminating, by adhesive, extrusion or thermal lamination, the sheets together to form a laminated composite sheet with the intermediate sheet laminated between the top and bottom sheets; and c) forming individual liners from the laminated composite sheet by cutting through the composite sheet in a thickness direction to form the plurality of individual induction heat-seal liners; each individual liner being an integral liner comprising an adhesive, extrusion or thermally laminated body characterised by the top, bottom and intermediate layers of the body being bonded to form a top closure-facing layer (20; 220), a bottom heat-seal bonding layer (30; 230), and an intermediate metal foil layer (40; 240) disposed in a thickness direction between the top and bottom layers lamination, the metal foil layer of each individual liner having a central opening (42; 242) surrounded by a metal foil portion (44; 244) configured to lie above a container rim (82; 282) surrounding an open mouth of a container body (86; 286), and the bottom layer having a heat-seal bonding area configured to lie above the container rim that is activated by heating of the metal foil portion to induction heat-seal the bonding area to the container rim, wherein the central opening in the metal foil layer is formed prior to the laminating step; and during the laminating step one or both of the top and bottom sheets, or a layer of adhesive used in adhesive lamination, fills or partially fills the central opening in the metal foil. a) providing top (20; 220), intermediate (40; 240) and bottom (30; 230) sheets for forming top (20; 220), intermediate (40; 240) and bottom (30; 230) layers respectively of a plurality of individual induction heat-seal liners (10; 210); b) laminating, by adhesive, extrusion or thermal lamination, the sheets together to form a laminated composite sheet with the intermediate sheet laminated between the top and bottom sheets; and c) forming individual liners from the laminated composite sheet by cutting through the composite sheet in a thickness direction to form the plurality of individual induction heat-seal liners; each individual liner being an integral liner comprising an adhesive, extrusion or thermally laminated body characterised by the top, bottom and intermediate layers of the body being bonded to form a top closure-facing layer (20; 220), a bottom heat-seal bonding layer (30; 230), and an intermediate metal foil layer (40; 240) disposed in a thickness direction between the top and bottom layers lamination, the metal foil layer of each individual liner having a central opening (42; 242) surrounded by a metal foil portion (44; 244) configured to lie above a container rim (82; 282) surrounding an open mouth of a container body (86; 286), and the bottom layer having a heat-seal bonding area configured to lie above the container rim that is activated by heating of the metal foil portion to induction heat-seal the bonding area to the container rim, wherein the central opening in the metal foil layer is formed prior to the laminating step; and during the laminating step one or both of the top and bottom sheets, or a layer of adhesive used in adhesive lamination, fills or partially fills the central opening in the metal foil.