Abstract: The present invention concerns a line projecting device that can project a line spanning 360 degrees onto a working surface. The line projecting device preferably comprises two line projectors back to back and a leveling device. The leveling device is used to indicate the horizontal position of the line projectors, both being in a same plane. Each line projector consists in a source of light that can direct a collimated light beam on a transparent annular cylinder. A plurality of partial reflections and refractions of the light beam inside the cylinder create a line that spans over 360 degrees on working surfaces in the line of sight of the projector.