Paulson did make two sample chips of this sort of thing but I don’t know of any examples being used in a casino. Here’s one:
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And the other I’ve only seen from I believe
@mipevi, it’s some sort of black chip with yellow dots and a horse on it, IIRC.
I know there are a few examples of Burt/ASM having done this, though the only I can remember off the top of my head is this dunes chip:
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And as I’m writing this I realize those might just be cancellation holes or ink marks of some sort, but you get the point. (Edit: definitely not clay dots)