In the US, think baseball cards, or cigarette cards.
But in Britain, when you bought tea bags in former times, you got a free card. They were on various themes, and when you got the complete set of 40, you could send away for a box to keep them in. Because the subjects were so varied, they provide interesting talking points, and also a bit of nostalgia for older audiences who will remember them.
Your spectator chooses a card, puts it under the box and puts the rest back in the box. With your back turned, you can know what card was chosen, and of course you can be shown to have "predicted" it.
The box is made of plywood and the electronics inside are charged wirelessly.
I can customise any set of cards to suit your local setting - you just need to provide me with two sets of each.