Not quite foldable... How about a single "cell" that is on an X-Y mount (or just X for a simpler single line display). Your finger "sees" only one cell at a t

Not quite foldable... How about a single "cell" that is on an X-Y mount (or just X for a simpler single line display). Your finger "sees" only one cell at a time anyway. As you used your finger to "skate" over the surface of the board, the "display" computer would read the X-Y position and drive the pins appropriately for that spot. Back to a one-dimensional (X only) readout with something like a scroll wheel on one side to scroll up and down seems pretty easy and useful. Picture a dot matrix printer where your finger is the "paper". The printhead would need a 2D set of pins, not just a vertical line... hmmm, maybe a vertical line of pins would be adequate in conjunction with the left-right sliding motion. Result: size is limited by the X-Y mechanical accuracy (backlash, rigidity) and cost would scale very well compared to size: one cell's worth of pin drivers for any reasonable size readout. [edit] Per Someone http://news.ycombinator.com/item?id=1842617 http://news.ycombinator.com/item?id=1842617, a X-only (line) readout with two heads, one for each hand (probably on the same platen) would mimic the Braille best. If you had a force sensor to sense the user pushing +/- in the "Y" dimension, you could use that to "scroll" the line without having to take your hands off the readout.