A laser line generating device, comprising: a housing (12, 14); a first laser light generator operable to emit from the housing (12, 14) a first plane of light having a fan angle and arranged in the housing to project the first plane of light perpendicular to a horizontal plane; and a second laser light generator operable to emit from the housing (12, 14) a second plane of light having a fan angle and arranged in the housing to project the second plane of light perpendicular to the first plane of light and perpendicular to the horizontal plane; wherein at least one of the first laser light generator and the second laser light generator further comprises a laser diode configured to emit a beam of light; a third laser light generator operable to emit a third plane of light having a fan angle from the housing (12, 14) and arranged in the housing to project the third plane of light perpendicular to the first and the second plane of light; a self levelling mechanism comprising a chassis mounted to an assembly; characterized by: the fan angle of the first plane of light being greater than 180°; the fan angle of the second plane of light being greater than 180°, such that the first plane of light intersects with the second plane of light along an axis of intersection; the beam of light being incident upon a reflective element having a cone shape, thereby forming a plane of light; the fan angle of the third plane of light being greater than 90°, such that the third plane of light intersects with both the first and second planes of light; the assembly being a gimbal assembly; and an inclinometer or other measurement device configured to indicate when the angle of tilt of the laser line generating device is near or outside of the range of the levelling mechanism, wherein the inclinometer or other measurement device is in data communication with a controller, preferably a microprocessor, that controls operation of the laser line generating device. a housing (12, 14); a first laser light generator operable to emit from the housing (12, 14) a first plane of light having a fan angle and arranged in the housing to project the first plane of light perpendicular to a horizontal plane; and a second laser light generator operable to emit from the housing (12, 14) a second plane of light having a fan angle and arranged in the housing to project the second plane of light perpendicular to the first plane of light and perpendicular to the horizontal plane; wherein at least one of the first laser light generator and the second laser light generator further comprises a laser diode configured to emit a beam of light; a third laser light generator operable to emit a third plane of light having a fan angle from the housing (12, 14) and arranged in the housing to project the third plane of light perpendicular to the first and the second plane of light; a self levelling mechanism comprising a chassis mounted to an assembly; characterized by: the fan angle of the first plane of light being greater than 180°; the fan angle of the second plane of light being greater than 180°, such that the first plane of light intersects with the second plane of light along an axis of intersection; the beam of light being incident upon a reflective element having a cone shape, thereby forming a plane of light; the fan angle of the third plane of light being greater than 90°, such that the third plane of light intersects with both the first and second planes of light; the assembly being a gimbal assembly; and an inclinometer or other measurement device configured to indicate when the angle of tilt of the laser line generating device is near or outside of the range of the levelling mechanism, wherein the inclinometer or other measurement device is in data communication with a controller, preferably a microprocessor, that controls operation of the laser line generating device. the fan angle of the first plane of light being greater than 180°; the fan angle of the second plane of light being greater than 180°, such that the first plane of light intersects with the second plane of light along an axis of intersection; the beam of light being incident upon a reflective element having a cone shape, thereby forming a plane of light; the fan angle of the third plane of light being greater than 90°, such that the third plane of light intersects with both the first and second planes of light; the assembly being a gimbal assembly; and an inclinometer or other measurement device configured to indicate when the angle of tilt of the laser line generating device is near or outside of the range of the levelling mechanism, wherein the inclinometer or other measurement device is in data communication with a controller, preferably a microprocessor, that controls operation of the laser line generating device.