All individual parts on the finished wing kits (ribs, fittings, etc.) and those on the quick-build kits are primered prior to assembly. The spar pieces (spar caps, stiffeners, bolt fittings, etc. are individually primed before assembly.

Here is a flap and aileron being drilled and clecoed in their assembly jigs

The leading edges are formed with this roller giving a very consistent, precise bend.