[Jordan Baker]

As for your cross section of the top channel. When I had mine made up at the shop they were trying to figure out how the original was done too. The first and second bend would be easy. The 3rd bend is the hard one since the first two bend would now want to close down onto the die. What the shop figures was done is the third bend was made until the first two closed down on the die, then the panel was placed into a form in a another press brake and then pressed down. One my sample you could make out the third bend wasn't as tight of a radius as the first two.