Yu-Gi-Oh! Day Question: What's these Official Picture Cardboards being used for? | tcgmode

We have an upcoming Yu-Gi-Oh! Day (SEA) and one of the participation prizes are these Solfachord Happiness Picture Cardboards and Mitsurui no Mikoto, Saji Picture Cardboards. Question, what's these Cardboards being used for. I mean, aside from being collectible items, I guess? Has someone ac...