Or a microdot on playing cards distributed to communist countries.. similar to this concept: https://bicyclecards.com/article/a-map-inside-the-cards/ https://bi

Or a microdot on playing cards distributed to communist countries.. similar to this concept: https://bicyclecards.com/article/a-map-inside-the-cards/ https://bicyclecards.com/article/a-map-inside-the-cards/