Awesome idea on using a laser level. I'd never thought of that.JKalchik wrote:J, if you want to find straight lines on that curve, use a contractor's laser level. Level the tank, level the laser head at the right level, and scribe at the light.
If you've got a few feet of clear plastic tubing, you can use the poor contractor's water level. Level the tank, and determine your starting point. Hold the tubing with the ends up in a U shape, fill with water so the level comes up to a few inches from the open ends. Hold one end of the tubing at the starting point. The other end of the tubing (still held up in a U shape,) will be level as you move it around the round tank end.