Abstract: A machine (1) for erecting open topped cartons or trays from a substantially flat blank of varying height and footprint dimensions, comprising a magazine 3 adapted to support a supply of flat blanks of predetermined dimensions, a vacuum transfer means for transferring blanks one at a time from the supply to adjustable transfer rails (4)(62)(63) for transferring the blanks to a tray forming section 5, means G for applying glue to the blanks at predetermined locations, the tray forming section 5 including a variable well 6 defined by wall means 11 to 18 which are moveable in two directions to adjust the size of the well and a mandrel 7 having portions 40 to 43 which are moveable in two directions to adjust the size of the mandrel, and a cylinder 45 for pushing the mandrel into the well to fold the blank into a tray, the well being open at the bottom to allow the formed tray to be pushed through the well and onto a conveyor 8 for conveying the formed tray away from the machine.