[smokel]

Perhaps you are thinking of Daniel Rozin's "Wooden Mirror" (1999)?

https://www.smoothware.com/danny/woodenmirror.html

[boredpudding]

That's a very good one, but in my case it was a huge billboard that was advertising movies and stuff.

It had cubes in different colors so from further away it would look like an image.

[benholmen]

Rozin was a direct influence on me! Seeing his stuff ~10 years ago got me thinking about unorthodox displays.