Super clever RGB wallpapers by Carnovsky, debuted at Milan Design Week. Of uber geek design standards – consisting of three separate patterns printed over each other. By shining red, green, or blue light on them, you can isolate and hide the different images (source).
I like this, reminds me of fun club lighting when I was at uni, one colour isolated at a time and invisble ink in flatmates room on walls and ceilings, only visible with UV lightbulb so landlord didn’t know.