A method of seaming together the edges of plastics sheet (10) by bringing them towards each other, leaving a small gap, and introducing a plastics strip (26) into the groove thus formed. The strip can be directly extruded into the groove so that it welds directly to the sheet edges. Alternatively, external heat may be applied, for example by a hot air jet just before the strip enters the groove, so that the strip welds to the sheet edges. The sheet, and possibly also the strip may comprise foamed plastics material. The seam thus formed can be rolled before the material has cooled so as to produce a flush joint.

This method can be used to produce tubular plastics bodies, for making into containers. Also disclosed is a method of fitting a metal end closure in which an outward flange on the closure is turned around the outside of the foamed plastics body and engages under an outward shoulder atthe rim ofthe body forming a circumferential seam, the material ofthe body being compressed between the flange and an upstanding annular wall of the end closure. An alternative method of producing a flush seam between plastics sheets comprises reducing the thickness of the edge portions of the sheets and then overlapping these portions and sealing them together. The reduced thickness areas preferably have complementary profiles.