Hi Johan Buvelot, I believe three cards were used to make this novelty. The two pictures with only the outlines of the pitcher and stein showing and a third card inserted between with plastic so that the pitcher and stein of beer is transparent and ties the two pictures together.
It is two cards with a space between them for a brownish grain like substance- not sand exactly- that pours like beer when you turn it from one face to the others. G Heileman Brewing of La Crosse WI made a really ornate version of this flipping card that I used to have. Would love to know if they exist with other brewers names on them? Andy