RE: Question building polyhedral wing, and wings in general
I'm having trouble visualing what you're doing but perhaps this will help.
At any dihedral joint half the angle needs to be on each butt joined piece. Otherwise the part with all the angle will not fit against the part with a 90 degree face. Trigonometry says that the angled face will be longer and won't match the face done at a right angle.
Is that what you meant? If not then what about a good close up picture?
These days I build the dihedral breaks and panels all in one go by using a pair of building boards angled upwards to match the dihedral angle. For polyhedral I start on one side and work across to the center and then over to the other tip by only cutting the spars and leading and trailing edges to length. THis way I build around the dihedral joints and can fit everything quite finely.