The lower wing section was created on the English wheel, similarly to the upper wing skin. However, it is much flatter from fore to aft, and does not have a leading edge return. The wing rocker in this shot looks acute - this shape pings back when the two wing halves are united.
Also note the central wing reinforcement panel - this holds an aluminium pipe to support the stand mount. It looks really spindly - but the tube gets reinforced later on in the project with a composite of 12mm 8.8 grade thread bar, 1 1/4” stainless steel tube and 3/4“ chrome moly tubing, all bonded together with special resin.