I have always wanted a multi touch display type thing. Your idea is nicely planned out, the only problem is that (besides being a little confusing) it requires a darkened box. Ive seen ideas from using a wii-mote (you cant make this up!) to IR light. As soon as I find an old LCD that is easy to take apart I intend to make my own version

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Wii-mote
Giant multi touch
Box version
You get the jist

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