600 ton Pacific press brake? I am not sure what you call such things any more. This green monster was 20 feet between uprights. Any way - you make the curves by bending on each ( or less) of those lines - just enough - not too much. Yes, you can see the series of bends.
Since its been 25 years, I may be way off on plate thickness
I learned how to do it as well in 8th grade metals class at Nokomis Jr. High school in Minneapolis, Mn. This would have been about 1970. The school is long gone now. Is my teacher, Mr Eide still around?