Hello @osama.elkholyBT3X6
I am sure Contour Roll will always produce a square when flat patterned.
Because it isn't a fold, and is deforming the material. I'm not sure Inventor could achieve this.
Their is a new feature which can unfold complex parts, called Unwrap. This will unwrap the part. But wouldn't unwrap as a sheet metal part, with sheet metal defaults.
I have attached a print screen to show you. You could unwrap, then thicken offset and save the face as a DXF. Which you can cut out.
If this is something you feel will work, and don't know how to use the feature i will do a screencast to show you.
Hope this helps.

Thomas Savage
Design Engineer