First test

I do not have an acrylic sheet so I used the screen itself. Like nima said here, using the TFT as acrylic should be ok. I wired 3 leds and here is the result (i'm sorry the quality is terrible).

The 3 dots are the leds, and you can notice blobs under the middle led. They are hardly visible, because there are 2 layers of IR filter and I forgot to remove one, but the blobs are visible when there is only one IR filter. Moreover, I have 5mm leds and the screen is 2mm thin...

The only problem is to avoid extra lighting. I used some basic paper, it stops IR very well and you can bend it.

I don't know how many leds will be necessary. My led model sucks (5mm, 940nm), but I'll try to continue with them. My next step is to build a led rail (25 leds) in order to run a real test.