The Spirit Deck by Birdy Cai, Jay Wang

In ancient times, people believed that every object had a spirit of its own. The Spirit Deck brings that idea to a deck of cards: an impossible fusion of card magic, light, and optical engineering.
Turning a deck into a solid object, whether crystal, wood, or another material, is a classic finale in card magic. The familiar cards become something unexpected. Birdy Cai and Jay Wang take the effect further: the deck becomes a transparent block, and light reveals the card that remains.

The Effect
Two participants each select a card. Both cards are returned to the deck and mixed. You perform your favorite card routine and reveal the first selection.
As attention turns to the second card, the audience discovers that the entire deck has become a transparent block. You describe what remains as the "spirit" of the deck: a memory of the cards it once held.
Shine a mobile phone flashlight through the block, and a clear image of the second participant's chosen card is projected for the audience to see.
The image is neither printed on the surface nor hidden inside the block. It forms entirely through the interaction between light and the block's internal optical structure.

A Different Approach to Card Revelations
The block appears clear and smooth. Within it, microscopic features created through advanced manufacturing techniques control and redirect light. Illuminate it from the correct angle, and those features form the image of a playing card.
An ordinary beam of light becomes a card revelation. The light seems to carry the memory of a participant's thought.