Build Circuit: Power + Wire Slide Dimmer + Wire + Branch + (Left Channel) Fan + (Right Channel) Wire + Servo + Long LED
Mount the Long LED & Fan on the side of the Cardboard Box. Cut a slit on the side of the box to mount the Slide Dimmer
Draw a picture of a girl/boy restroom sign on the front side of the box.
Cut a slit on the top of the box. Draw and cut a circle from a sheet of construction paper. Mount the circle on to the servo. Slide half of the circle through the slit.
When someone is in the restroom, just slide the dimmer so that others will know that you are there.