<HTML>I believe you can project a curve with a laser level, as long as it's one of the rotating types.  To project a curve with the center higher than the ends, position the laser below the level of the projected line.  The projected line will then be a parabola.  The more the difference in height, the sharper the curve of the parabola. Whether that might be close enough for government work on a garden variety Steinway, I would think so, but others may disagree. Loren Hedahl</HTML>