An indicating apparatus includes a base arranged to contact a first surface of an opening in a wall and a second surface of the opening in the wall, the base being rotationally stable when contacting the first and second surfaces of the opening, and an indicating member coupled to the base, the indicating member having a first portion arranged to indicate a first line along the wall when the base contacts the surfaces of the opening, and a second portion arranged to indicate a second line along the wall when the base contacts the first and second surfaces of the opening, the first line being parallel to the first surface, the second line being parallel to the second surface.