I got fed up with trying to see the lines I draw on metal with pencils or coloured pencils or just scratching lines so I went to the dollar store and got a pack of mackers for a couple bucks. They worked ok but then I saw white markers at princess auto for a few dollars more for one.  I bought one and it lasted over a day or two and went dry and I hardly used it.  My point is, you might like the markers from the dollar store if you need to mark metal. I've had them for a year or two or three and all still work fine.