For proximity and 3D, there's also the not-yet-released Tactual PRISM keyboard[1] with depth sensing. And optical tracking.[2] Though that last millimeter of "

For proximity and 3D, there's also the not-yet-released Tactual PRISM keyboard[1] with depth sensing. And optical tracking.[2] Though that last millimeter of "is it actually touching or not quite" is hard to do without hardware support from the keyboard. [1] https://vimeo.com/258421095 https://vimeo.com/258421095 http://www.tactuallabs.com/ http://www.tactuallabs.com/ [2] https://frl.nyu.edu/multi-touch-with-realsense-camera/ https://frl.nyu.edu/multi-touch-with-realsense-camera/