Abstract: A pouch containing a gas is formed by drawing a first elongated sheet of gas-impermeable material from a supply of the material in a drawing direction. The sheet has a transverse profile perpendicular to the drawing direction that includes a channel. A second sheet of material is drawn, such that a first portion of the first sheet and a first portion of the second sheet are substantially parallel to each other. The gas is injected between the first portion of the first sheet and the first portion of the second sheet. First and second lengths of the first and second sheets are sealed to each other, where the first and second lengths are substantially parallel to the drawing direction, to form first and second side edges of the pouch. Third and fourth lengths of the sheets are sealed to each other to form first and second end edges of the pouch.