Ball bearings in a strong magnet field can make shapes - video
Scientists invent a machine that controls tiny ball bearings in a powerful magnetic field to precisely draw 3D images.
This is amazing, each ball bearing must be manipulated by its own magnetic force .... how?
I suspect there must be on the floor, or ceiling, some way of transmitting a field directly up, with one field for each ball bearing. Then you have to
change the strength of that field to move each ball.