Developed by Laurie Cook, this is a precision tool that evolved from the standard ruling pen. Featuring a large reservoir and polished brass blades that glide easily over paper surfaces in a comfortable, waterproof, stainproof polished handle, it performs like a pointed brush or a variable monoline pen and is also excellent for gestural drawing. Open and close the screw for thin to thick lines; lay it partially or completely on the side for a variety of wide strokes.