To the aligning issues from molding A 3D printed exoskeleton jig would be a solution. A jig who installs to known points and then aligns the mating parts. I made this jig to cut propellers... Or this jig to drill helicopter boomsApr...
All structural components were fabricated separately and oven-cured before being adhesively bonded in an assembly jig. Steel lift pins were mounted to the root rib prior to final assembly to provide shear load transfer from the wing to the fuselage, as seen in Figure 4. Further details ...