Non-So-Expensive MultiTouch Table

For the Communitas Project I need to know more about touch Tables.
So I follow this Harry van der Veen´s “FTIR multi-touch display how-to guide”

It´s really strait forward and don´t bring me much complications until the very end of it. Seams that It´s need a Rosco Gray surface and ELASTOSIL® M 4641 silicone. Those materials a really expensive and hard to find. So I start looking and exploring for other alternatives.

Finally I use a shower curtain a diffuser in the middle of another acrylic.

Here is the final assembly video.

Here are a video of other materials that could bring interesting effects. I´m using my application made with Processing call JoyOfLight for recording the finger blobs.