Recipe: Take (1) old flatbed scanner. Add fluorescent paper to to the glass, add (8) ultraviolet LEDs and various motors. Yield: one unique multi-line display that is nearly impossible to photograph. Messages appear briefly in eerie green, glowing letters then fade.
Technical details: PIC, RTC, dual L293D motor drivers. 8 UV LEDs on small board, mounted with hex nuts on a threaded rod. A DC motor coupled to threaded rod moves the LED platform vertically in the scan bed, allowing up to four lines of text. Original stepper motor and belt drive was retained to control the horizontal axis, and text displayed in dot-matrix fashion similar to POV devices.