I considered wanting my Clown Nose to blink to. I found the thread for making that gizmo but for me it was also too complicated.
However a trip to Dollarama I found one of those fake security cameras that blinks a red led every few seconds. It runs off a 9v battery. I figure I can salage the guts from there and put it in the car....But then I realized I do not want to mess with that mirror cover....