Abstract: The invention relates to a method of producing containers such as envelope wallets and folders or the like, which comprise at least two outer wall components (4,6) margins of which are bonded on three sides of the wall components to edges of a flexible extruded plastics material strip (12) which in the example given is polyvinyl chloride, and which has a V-cross-section or a W-cross-section and forms an insertor gusset. The container may have at least one interior wall component provided with adjacent inserts (12) bonded to neighboring wall components. Dielectric heating may be used for the bonding step and suitable apparatus is also described.