All work in metal requires prior marking with stylus, with compasses, etc.. with steel blades. Plotted scratches or points are hardly visible due to their very narrow width. Therefore, after tracing, we should drag the scratches with ordinary school chalk and blow off its excess. It will only remain in the cracks, and thus make them clearly visible even in low light. Instead of chalk, you can use a small scrap piece of drywall.
