@ Potozky - thanks
@ Erik - right, Halinski designs with such small tolerances that the structure parts have to be glued very precisely so that the skin parts fit tightly around. I learned (the hard way...) to cut the parts, particularly the rib's front end, a bit inside the line. Shaping the skin parts before gluing and using cellulosic glue reduces the risk of marking the skin. Putting pressure with something stiffer than a finger (like a steel ruler) helps, too. It ensures that the force is concentrated where it can be resisted, without deforming the skin part
As usual, I glued the main wing skin parts together before assembling them to the structure. In my view, this sequence helps to achieve a good alignment. The landing gear emplacements give good clues to get it well.