Interactive led cube

Projects General Guidance
1

I've built a 5x5x5 led cube for my daughter and I was looking for giving it some kind of interactivity.
Recently I found this and became amazed: Interactive LED Cube on Vimeo

So I'm playing with the idea of using the plastic cube surface as a sensor of some kind to detect hands moving around it.

The first idea was using light changes as a reference, but that will have the problem of the interference of the light produced by the cube itself.
Ultrasound or IR optocouplers are quite bulky and expensive. So I thought about capacitive sensing, using this library Arduino Playground - HomePage.

The thing is: will some thin wire loops on the inside of the cube's acrylic cover work as capacitive sensors?

2

I've covered the inside of the fiberboard box used as base of the cube with aluminium foil and turned to be an easy capacitive sensor.
Now I'll have to think about to display the data in a nice way.

3

Cube in the video is huge and 8x8x8. I 'm doubt you can get the same level interactivity with small cube. Second, the man in video using touch screen, so he has 3D data, xy and pressure for z. You can't get this data from capacitance, which basically 1D, or 2D if many of them.
Have you research on normal touch screen, which transparent, like on smart phones ? Probably, you could glue 6 on each side of acrylic cube (I'm guessing here, size of your cube 15 cm side?)