A Modified National brood box comprises two outer walls, two inner walls, two top locking bars and two bottom locking bars. Also included are a pair of frame runners and a pack of nails. The outer walls each have two long grooves and 4 cut out slots, the inner walls are plain and slightly smaller.
Start by attaching a frame runner to each of the inner walls. Attach the runner to one edge of the inner wall using the brass escutcheon pins ensuring that the runner is spaced equally from each end of the side wall.
Apply glue to the grooves in the outer walls and then push the inner boards into the groove, ensuring top of runner coincides with mark.