Which drawing instrument is used to create thick, bold lines in engineering drawing?

A drawing pen or marker with a broad tip is used to create thick, bold lines in engineering drawing. These pens are specifically designed to produce wider strokes and bolder lines, allowing engineers and designers to emphasize specific features, outlines, or sections in their technical illustrations. The broad lines provide visual contrast, clarity, and emphasis, aiding in the understanding and interpretation of the drawing. They are particularly useful for highlighting important dimensions or distinguishing different parts or elements within the drawing. The use of thick, bold lines adds visual impact and helps draw attention to critical details, ensuring effective communication of the intended design information in engineering drawing.