What's cool about the card, and I mention this in the book, is that the edges of it have embedded foil. I asked about where the foil came from and they told me it was from the foil scavenged from yogurt cup tops. The whole thing is adhered together with glue from some old prison recipe.
Technically, the card is considered contraband, as anything the inmates physically make is considered contraband.
It's one of my most cherished possessions.