Abstract: Apparatus for packing rows of flat articles, such as side-seamed folding carton blanks, in a box. A flat table top is provided with a cavity in the packing region which receives interchangeable inserts. Sets of rear abutment fingers and front compression fingers are mounted for vertical movement between hidden retracted positions and operative raised positions protruding through apertures in an insert. When the operator slides a first row of blanks to the packing region, a switch in the table surface causes a moveable wall to be extended and the rear fingers to rise. Another switch near the rear fingers causes a modular drive mechanism to extend the front fingers and then move them longitudinally to compress the row of articles. A nozzle blows a stream of air across the insert to hold a divider in place against the edge of the compressed row. A second row is then arranged against the next set of rear fingers and the divider, as a second set of front fingers extend and then compress the second row.