I rolled the billet down to this thin sheet.
I could see the centre of this billet is fused through the cut surface.
So I started punching on the back side for making pattern (This time I punched letters). At this stage, the letters were not clear to see.
I rolled it down, punched it, and sanded its convex surface. I repeated this process more than 4times… and finally, the letters turned into visible…