Spent more time fettling the wing tips today & the edges of the wing end rib skins need to be sanded to fit properly, I still need to sand a little more off the left one so as to provide a parallel gap between the aileron & the tip. Once I'm happy with the fit, I'll rivet the left tip on. I used a combination of a string line & laser level to check the alignment of the flap, aileron & fixed trailing edge sections of the wing. They all seem to align well enough that I think I would only cause damage if I were to attempt to improve things.