When doing layout on metal use a needle sharp scribe. The thinner the
line the better. Now take a broad tip sharpie and color the entire
surface of the metal. I use a blue color as the black seems to
reflect light a bit too much. Now do your layout with the sharp
scribe. I like to lay out the finished dimensions I need for the
piece. When you do your cut out make sure you finish just up to the
line. This way you know exactly the dimensions of your cut out. If you
cut inside the line you never know if you have drifted one way or the
other. Make sure your scribe lines are light enough to polish out
after cut out. Also the sharpie washes off in alcohol. Frank Goss