They are not cast in a way that for every cymbal there is a round casting which is then rolled out. Of course every alloy was molten in the beginning and then casted into a form. But this is what Paiste does differently than the others: the raw material for the cymbals (talking about 2002 and Signatures here) are round discs stamped out of sheets which were rolled in a mill. You can clearly see these raw discs and how uniform they are in the video on the Paiste website. And if you take a look on a finished but not lathed cymbal you can clearly see that the raw material was a sheet rolled in one direction. I own a Dark Energy Dark Dry Ride where you can see the direction and the uniformness quite clearly. Not sure how that might be different for the B20 Paistes as B20 for my knowledge can not be rolled to sheets in a mill. But for B15 and B8 I‘m sure about that.They believe they are cast like most others. Paiste just doesn't have an "in house" foundry so when they get to the Paiste factory they are discs of a very specific weight and thickness. Then the hammering, shaping and lathing start. All part of the quality control.