FTIR table DIY

I want to build an FTIR (frustrated total internal reflection) table. It looks fairly simple to build, and the result is a quite-sophisticated multi-touch interface that can be used for a variety of applications.

click image to go to source site

Here's a diagram that illustrates the FTIR principle:
image from Jeff Han

And here's a link to my delicious bookmarks on the subject: FTIR links