[joemi]

This is pretty cool as-is, but I can't help but try to think up ways to increase the speed. (Not the point, I know.) I feel like it should be able to do a whole column pretty quickly with some optimizations. If the device that turns a block could do so without needing x-axis alignment to change, then you could do a whole column pretty quickly. Or perhaps it'd be better to do rows instead of columns, since the y-axis alignment shouldn't need to change with the current device. As for the block-turning device itself, I think some sort of thing that rotates would speed things up since you wouldn't need to reset, I think. I bet a manufacturing automation specialist could get this thing cruising...

BTW I love that you initially went with a very direct e-ink analog with the balls!

[leoc]

If you had a rotating mechanism which allows slip then you could have rotor shafts which rotate all the blocks in a column while braking mechanisms prevent all the blocks in a given row from moving. Or you could have both rotor rows and rotor columns if you implement a rough mechanical equivalent of the hysteresis systems of ferrite-core memory. Or (I think GistNoesis suggested something similar https://news.ycombinator.com/item?id=44794092 ) if you hide a neodymium permanent magnet just under one corner of each of the blocks you could use a pair of electromagnets behind that block to pull the block from either orientation into the other, almost a solid-state solution apart from the axle the block would rotate on and potentially one which could set the entire display at once.

[benholmen]

Thanks for thinking through it! I've found that moving left-right is a little noisier and has a little vibration - up-down is smoother. However, it's not that noisy and it'd be fun to experiment with different algorithms for finding the next pixel.