I've been working on something like xanadu's cool light printing (Parallax Forums) with the S2 using only an unmodified S2 and the GUI (tape to cover the Power LED and DB9 for Light Bleed) - Two column LED pass for the top of letters, a 180+ degree with correction turn and alignment, and a Three column LED pass for the bottom of letters. I am working on alignment now and then will shoot a long exposure photo - fun stuff (trying to do more with less via erco!). I was also going for HELLO! - 5 LED high (column) X 4 LED wide (row) matrix per letter, two column gap between letters.
Okay - here is the best effort yet on the EXTREMELY low-tech LED Dot Matrix printer for the S2. Again, the only modification to the S2 is tape over the programming port and Blue Power LED to stop light bleed.
Code is written entirely on the GUI and uses Sub-routines for different LED configurations. The time-lapse photo is a bit shaky because it is over 2 minutes long. Remember to that this is a pass left to right for the top of each letter, a turn and a pass right to left for the bottom of each letter - alignment and rotation of that critical turn are done by trial and error - only in the GUI!
See photos. (Software version 2, Trail 3.1).
Edit: Just noting that the gap on the "O!" is on the side following the turn - so, to fix this - the turn should be tighter and less final rotation - that way, the "O!" should be more closed and the "H" will not be compressed. Otherwise - alignment is pretty good.