One of the more critical steps for this section is aligning the cabin floor with the aircraft centerline. I went to Home Depot and bought a self-leveling laser device that will project a vertical and horizontal line (one, the other, or both at the same time). This is a great way to get the whole structure perfectly aligned. I'll be able to use it for all kinds of leveling and centering tasks on this project, as well as plenty of stuff around the house. After careful measurement, I also began placing the center spar on the cabin floor. It's funny to finally be placing a structure I built two years ago into place. The more amazing part is that everything FITS!
