Mounting the wings.
Some other builders that I've spoken to said to allow a day to install the wings, well it took me nearly two days. It's only four holes that need to be drilled, the actual drilling of those holes didn't take all that long maybe an hour at the most but getting the wings rigging angle, square and fitting properly in the spar tunnel took forever and some inappropriate language! I'd made a mistake and had riveted the short angled reinforcing bracket into place which beautifully obstructed the head of my drill while trying to drill the main mounting holes. As I had gone to so much trouble to set the wings in place, it was an easy decision to cut off the offending angle and make up two new ones after I'd finished. For all that effort I am extremely satisfied with the whole thing millimetre perfect.