For typical CAD, the typical request is for flat patterns of individual components.
It does not appear the smoothly curved domed roof has individual components -and- having curves in 2 directions, cannot be created by flat parts. Almost always formed parts will require added margin material to hold them when being stretched to produce the 2-way deformation and then trimmed to final outline.
In the examples on the Ametank site I see a roughly domed roof that has clearly individual panels that appear to be simple bend, not deformed. I don't see any panels on the provided image. See