Altium has flex/semirigid support, including bending points so you can have an assembly fold up on itself, or in an enclosure etc. I don't think you can twist a section lengthwise, just a straight crease of given angle. So if you aren't using that kind of bend it should be fine.
I don't know that you'd want to fit a board into an existing model yourself, versus getting the board outline from mechanical engineering -- but given enough adjustment, checking back and forth between the 3D model and the folded board, you can do that, I'm pretty sure.
Tim