All the ones I built had steel rods sticking out about 4" from each side of the fuselage and aluminium tubes in the wing, so you just slid on the wings, then there would be some sort of retaining mechanism, like a hook that went through a hole in the fuselage (within the wing root, so hidden when wing is assembled) with an O-ring or rubber band to stop the wings sliding back outboard. If the wing sits on top of the fuselage, they still have the steel rods and aluminium tubes as a joiner, but instead of the hooks, each wing has a peg at the front that goes into the nose part and a single wing fixing bolt at the rear. I guess these days, you can use carbon fibre tubes and rods.