Welding and Metalworking - Help with fabricating trailer roof

I am building an enclosed trailer and the plans I have show a flat roof. I want to build a bowed roof and can get the bowed roof beams with no problem. What I need to figure out is how to bend my flat sheets of galvalume with a 6" radius on each edge to conform to the bend of the roof bow. Is there an easy way to do this or do I just need to use a long slip roller on each side to do it?

Does anyone know how they manufacture these type of rolled roofs in the trailer manufacturing industry?

It is easier to do if the radius needs to be right at the edge of the sheet. Basically you roll the metal around a piece of pipe. Find a piece of pipe that is the same size or a bit smaller than the radius you need to roll. Then figure a way to attach your sheet to the floor or a bench and figure a way to attach the edge of your sheet metal to the pipe.

If your sheet metal is thin enough duct tape or packing tape along the full length with extra layers at the ends may be strong enough to hold it to the pipe. If the sheet metal is thicker you may need to run some screws into the pipe with a washer under the head. Slide the edge of your sheet metal under the washer and tighten the screws.

Now secure your sheet metal to the floor or workbench with weights or clamps. Now you press the roller down down on the floor/bench as hard as you can and roll the pipe. You may need friends with one on each end to provide rolling power and a friend or two in the middle to push down.