With the pilot's booth in situ and the spars bolted together (including cross-members adjacent the booth itself), apply the 0.5mm panels either side. You'll get through a lot of 4 x 12mm pop-rivets in all of this ~ and I often buy the full box of 1000 pieces ~ but then remember there's three-quarter million rivets in a 747 and three million in what is left of the Titanic. And when you think about it, both were a resounding success... not least in the latter's case for being the only ship most of the world has heard of.
