Just yesterday I laid my flat SS down on the fab table. Grabbed my center punch to mark out some holes to drill in some sheet steel. Noticed it wasn't sitting flat on the table. Figured it was warped. Center punched the holes, grabbed the flat steel to head over to the drill press.
I now have pieces of flat soap Stone and found out the sheet metal was not warped.
Have both...havn't used round in years (wasted money on a holder cause they looked like they would help)...flat easier to follow a straight edge like a carpenters pencil.
Flat soapstone. In a holder. Sharpen it to a bevel on the side of your grinding wheel. Push very lightly make very precise marks. Sharpen often, soapstone is cheap.
Doing iron work I used flat for torch work. When mig/tig welding automotive type stuff where I'm not cutting with a torch, I just use a Sharpie or scribe.
This. I tried most everything, even the silver streak regular pencils but the "silver" was brittle in those and they didn't last. But the silver streak mechanical holder is perfect. $17 on Amazon
Silver Streak is $11. at TSC but when I needed replacement lead they didn't stock it. So another pen was purchased, then another, now they have the lead. At least I can usually fine one of the pen's, maybe.