Those of us who have been in the hobby for a while have seen them. I emphasize for a while because your scan shows metal blanks, something not likely to be found for sale in any public venue today. Making the blanks available, in hindsight, may well have fueled the actions of people to create fake chips. It would be easier to fill in the blanks than it would be to scrub the plastic out of real chips to create blanks.

Thanks for including the blanks in your scan. I'm sure many folks never knew they were available for purchase not that long ago.