The disc cut from a sheet
It is the easiest to identify, because it carries the marks of how it was made. It is a flat round, cut out of a sheet of material. Its surest sign is the edge. The edges are sharp, almost square, cut at a hard angle. Sometimes they have been deburred by hand, which leaves a slightly uneven, somewhat rough finish.
Zoom in on the edge with a good phone or a microscope and the clean cut is obvious: the cut of a sheet, not of a moulded piece. Above all, the disc is perfectly flat, with no relief at all.



















