So say I make an XZ array of passive flip squares and I want to be able to spin them with a single "moveable" active element like a solenoid or servo. Mechanically how does this work? With my initial prototype I would have somehow had to reliably latch onto the slider bar in such a way that it could be pushed or pulled. Feels like this would be hard to do. So here is one way to simplify the problem.

I changed the mechanism from push-pull to push-push. All I need to do now is move some sort of linear actuator into the correct position and activate it to set the element to either black or white.  I'm not sure it matters at this point but with this mechanism if an element is already black say and you try and set it to black nothing happens because the slider is already pushed in. But this leads to the question "Does the write head (linear actuator) need to be able to sense the position of the flipped square?".