That's really nice. You should give it or sell it to science museum or 50 and make them really big!
Thanks! That is the plan.. I created the demo to pitch to interested people.
you could get an old microsoft surface 40 inch screen, the entire display is a video stream under linux with the sur40 kernel module.
That would be hard to source / use, as It's a bit dated. But the technic behind it could be replicated. It uses IR LED on the bezel, around a glass. With total internal reflection the light only shows up where you touch the glass. Then film that with a camera. The advantage to my method, you don't get interference of objects hovering above the screen. But getting the camera & display behind the screen, could be hard.
I've just done something similar with a Object tracking + IR Floodlights and one of VA Imaging's MER2 cameras. We have had some fantastic results with objects sat on these "Interactive Dance Floors" from Alibaba. Didn't even need the IR Absorbing film to get decent tracking results using OpenCV @ 300fps or so.