>Let people send you their 3D models or 3D scenes and you'll send them a hologram of it.

Oh hey, I have worked in exactly this business (taking people's random 3D models and bullying a rendering pipeline into feeding a digital holographic printer). It's hard, for many reasons. Mainly it's that holograms are expensive in materials, labor, and capital outlay (adding up to several k just for something the size of a piece of paper), and mass production of digital holograms isn't really possible without massive further outlay - writing them is time consuming, and copying them is fraught. It's like being a graphic design / print workshop, except everything is way more fiddly and expensive and nobody wants your product.

Analog holograms are a bit more tractable. But that's even more niche on the consumption end.