Abstract: Arrays of articles are stacked one on top of another in a U-shaped shroud structure which includes vacuum means to retain the upper array while the lower array of articles is positioned therebeneath. A carton blank is simultaneously fed from a stack to a position over the pocket of a intermittently operated conveyor. A vertically reciprocable mandrel forms the flat blank into a U-shape in one of these pockets. Both the mandrel and shroud are mounted on a shifting carriage so that as the mandrel is moved to an inactive position, the shroud shifts the arrays of articles onto the bottom panel of the U-shaped carton blank. Flap folding devices then fold certain of the end flaps of the carton and the shroud is then raised clear of the partially formed box so that the top panel can be folded. The manufacturer's flap and certain other end flaps are then folded up and the box conveyed by the pocket chain conveyor to a horizontal compression unit.