FTIR Touchscreen Hardware FAQ What kind of Acrylic are you using? I am using a 1/4" piece, measuring 24 x 18. I also polished the edges. It can be purchased at any glass / window store usually. How many LEDs are you using? Right now I have 42 LEDs, but I think you can get by with much less. Probably 14 will do. What kind of LEDs are you using? I am using some IR leds I bought off ebay. They are 8