curve

Anyone know how to do a pattern on sheet metal that is not a flange, its a roll or some other form? I understand how to do a pattern on a solid and extrude it but, how about doing the same on sheet metal?The extrusion needs to done on the flat surface not on a sold. Here is an example

I've been playing around with the opFitSpline function. One of these days FeatureScript will support on the fly parsing of user entered expressions. In the meantime, this FS will generate some fun 3D curves. https://cad.onshape.com/documents/5780f7f7e4b0b759b32cbbb9/w/6ae742fb5da12d92cd4e4ddd/e/aab0024ce36028e8b6ef4faf