This tool cuts two parallel lines into the surface of a peel coat sheet. The distance between the two blades is set with the thumb wheel in the centre. It was perfect for cutting a wide band like the administrative boundary verge seen here. Tricky to use, positioning was everything, draughtsmen had to have a light hand, to avoid cutting into the base sheet, and maintain a consistent level of pressure to ensure that the ruby ‘strip’ was cleanly cut. Requiring subtle adjustments in alignment, to keep the boundary line central, progress was surprisingly slow.