[HPsquared]

I suppose these shapes could be made incredibly detailed. There must be some kind of application for that.

[isoprophlex]

Its basically a bespoke diffraction grating printer, indeed. So, you could probably print holographic images?

[_def]

This github issue mentions a paper about holographic images on a DVD: https://github.com/arduinocelentano/cdimage/issues/14

But I can't actually imagine what it would look like. Sounds amazing though!