Fantastic effort, but oddly and almost shockingly archaic. This is seriously the way the problem is being solved? Why isn’t it microelectronics or MEMS? If we can print 3μm OLED pixels surely there’s a way to lift a discrete 1.6mm dot, especially with that huge 2.5mm spacing. Even adjacent dots ought to be no big deal. Maybe a haptic kludge or grid of air pressure nozzles? I have a personal theory of invention that s…
I was thinking if the dots need individual actuators. I'm old enough to remember dot-matrix printers; take the print head but put slightly beefier pins on it, move it left and right and use it to push metal spheres up in a hour-glass shaped cavity, with springy walls in the center section.
Obvious problems: how do you reset the spheres? And wear issues.
Edit: You could replace the hourglass throat with a plug valve (shared between pins). Print head comes along, turns the valve open, pushes the necessary balls up, closes valve, moves to next column. Needs more mechanics per cell, though.