The word in the centre spells 'Braille' and the top one is 'Flickr'. You can see how the Ls look like an ordinary lower case 'l' and also notice the 'i' and the 'r' in each word. It was on an ordinary sheet of white card but I added some colour in Photoshop (well, you all know me by now)! Not a particularly satisfactory result but I intend to try this again sometime.
1/4 sec at f/18 (ISO 100)