I am in the process of assembling a Barrett (E38) GWR clerestory (brass) coach kit. They invite you to put three bends in the bottom of the coach sides to form a built - in solebar. There are only two half etched lines where two of the folds would go, and the coach is quite long. I thought that making three long folds would be impossible for me so I substituted a piece of brass channel, having made just one fold.. But I'm left wondering what an expert would do? I have yet to ask Barretts.
Well I'm not sure what an expert would do but I'd add the missing half etched bend line with a Tamya Olfa plasticard cutter. I bought mine from Squires years ago and it has done sterling service scoring lines on metal and plastic without needing its blade changed.
You can also deepen half etched lines with this which is handy when the metal is hard or thick and you want the fold to go easily. Reinforcement with soldered once the bend is made might be required to stop the metal reverting to flat again or at least acting like a hinge but that's easier than making the fold sometimes.
Of course if I screwed this up I'd replace the metal with a bit of channel, but I'm stingy enough to try making the extra line first.