This is a “holographic” display made of fan blades:
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Each blade contains hundreds of LEDs:
Here’s an explanation of how it works:
And here’s a demonstration model from HyperVSN, one of the larger players in the space, with each individual fan costing upwards of $3,000:
The thing no one mentions in any of the videos is: How noisy is the thing? Then again, since fans moving at a steady rate produce a predictable soundwave, I suppose it would be easy enough to rig up a noise-canceling speaker.
Source: core77