That was so many years ago when I developed it. Based on an idea for producing multiple coins from a pack of cards that was published in an issue of APOCALYPSE (it must have been around 1978 if I’m not mistaken).
I redesigned the gimmick and the process produced a couple of full waste paper baskets. But I think the result is quite respectable. It is thoroughly practical. Try to figure out your own solution to this problem!