Multitouch display, build your own: silicone rubber and a wooden frame

Finally I decided to build a wooden frame for my multitouch display. Basically I'm trying to build a light frame that may hold the plexiglass with the alluminium frame holding the IR LEDs together with the projection surface and the compliant surface that I'm going to make with silicone rubber. Here you can take a look at the actual stage of the wooden frame, it is quite complete, the glue is drying! On the right side you can see the silicone rubber I bought to make the compliant surface.

Once the frame will be ready I hope to handle more comfortably the display so I can go on at least with the software. That's because actually I do not own a video projector, I'll use just to test the software behavior.

Next step, as I was saying, will be the compliant surface. Actually the rear projection surface has a bad coupling with the plexiglas. This means that I need to press quite hard on the display in order to have workable "blobs" or decent reflected spotlight under the finger touch. I'll prepare a thin layer (1 mm) of silicone rubber to place beetween the plexiglass and the rear projection film, so the silicone rubber itself will be the material that will set off the FTIR effect and reflect IR from the pressed areas. This material seems to have a very good coupling with the plexiglass because it is so smooth and adhere perfectly without leaving micro air bubbles beetween itself and the plexiglass when pressed on to it. Of course this is also an hope!

As the great suggestions from Gravano's blog, I'll put the silicone rubber on the plexiglass panel and flatten it with an alluminium bar (it will be one piece of the alluminium frame holding the LEDs). To be precise I have to use some guide at the sides of the plexiglas that needs to be 1 mm higher than the plexiglass itself. Actually this is my problem: where I can find stripes of whathever hard material that are about 11 mm thick?