Gareth over at Parallax forum built this UV LED drawing Parallax robot:
I have replaced the pen slot with a bar of downward pointing UltraViolet LEDs one placed central to the hole and the others fanning out…..
This arrangement means that i can send the Propellers internal character-set (no costly data tables) to the UV array and plot to a Phosphorescent screen.
Via Hacked Gadgets.