I actually had a simular idea
A few years ago I was projecting an image onto a 2d grid of small ball bearings.
The intent of this was to be able to control not only the overall brightness at each pixel (or bearing), but also to control the angle of light reflecting off the bearing.
From a distance, this produces a genuine 3d image (not stereoscopic). One observer would see one image from one angle, while another observer could see an entirely different image.
I imagined having an entire circular room with these reflective ball bearings, with numerous projectors/lasers shining down at them from the ceiling. This could project any scenery onto the wall in 3d. Unfortunately my resources limited my prototype to a tiny low res grid. I considered using refraction through glass instead of reflection, but I was ill equipped to manufacture a glass pane with millions of dots. Among some of the alternatives I came up with was to shine the lasers through falling water drops, but this was much less practical that a fixed grid.
I'd have so much more fun with these side projects if I wasn't bound to my day job.