See through wooden sign

 Today, a client told me he wanted signs to guide his customers through his bar. The signs where to be subtle, but still clearly show the direction. They must also be able to blend in with the rest of the interior when not in use.

After a day of experimenting, this was the result, a wooden slate milled so thin that light pass through from the inside, leaving people puzzled when it turns of, only leaving a clean, untouched surface.