The original 'Template' was drawn on 11" X 17" paper with the 'ground plane' and a horizontal datum projecting rearward from the 'Max. Camber' point.
By knowing the actual ballasted height of a vehicle,reasonably accurate dimensions can be measured (in scale) at any point on the drawing,producing the necessary vectors for bulkheads,formers and stringers which define the new form.
Photo-enlargements can be stitched together with invisible tape to add 'resolution.'
A full-scale 'french-curve' of 1" Schedule-40 PVC pipe can be laid over the bulkhead stations to provide vectors for any longitudinal point along the 'Template.'
Long ago,cars were developed from full-scale blueprints.You'll see this in Martin Scorsese's movie 'Tucker The man and His Machine,' and the depiction of Alex Tremulis' blueprints.
Low tech will work when all else fails.