Foil

the rainbow is in the angle, not the ink.

a holographic die-cut sticker: tilt it toward your finger and the colour runs, because it was never on it

A holographic sticker has no rainbow printed on it. The foil is a stack of layers thinner than a wavelength, and the colour you see is the light that survives bouncing between them, which depends on the angle between the light, the surface and your eye. Change the angle and a different colour survives. This sticker is that geometry written out: a die-cut shape, a rim, a foil whose hue is computed from the reflection vector, and glitter facets that only flash when their own tiny angle lines up. Tilting it is the whole lesson. The photo-to-sticker half of the idea, from Yuwen Lu’s sticker-shader, is what the creator platform would add.

Concepts: color, light.

An interactive you play with one thumb, on Wundr.