Now that the whole wing and centre sections are complete, it is time to cut the locations for the fitting of the stringers that are so important to the shaping and covering of the wing. The simple technique after careful measurement, and two vertical cuts at the rib, is to score with a sharp knife horizontally then grip the cut in an adjustable spanner, wiggle and break a small square of wood out. Then finish with a square file! The stringers are of tapering widths towards the wing tip so need butting joins.