The stacks of cups are brought in the lot preparation area on an intermediate disappearing plate. When the preset number of stacks is reached the bulkhead that forms the plane opens and lets the stacks fall on a plane underneath. This operation is repeated many times to obtain the desired number of stacks. At the end, a pusher introduces the lot in the box previously formed. At the same time, the pre-glued cartons are taken from the store through suction cups, squared, pre-formed and positioned in the filling area. Then the pusher inserts the cups inside the carton and the flaps are closed by PVC tape or hot-melt.