Bottom of center wing with the four 4-40 screws that hold the wing tips to the plane
I use two 1/32" ply rib caps, then slide the wing tips in place with epoxy on the tip side and center side of the 1/32" caps. Slide the tips tightly into place and lock them, then there will be no gaps and the assembled wing will look like one seamless piece.
Indentation marked with an arrow was made by tapping hinge rod at wing tip. I'll make a pocket there. This is so hinge rod can be accessed to remove the aileron without major surgery