Most of them are rolled and crimped metal trailer siding, I have heard of a few being rubber.
There were a few people who had wall relamination quoted and it was pricey, in the thousands, so I bet the roof won't be far behind that if not more, personally I would tackle it myself. I have a delaminated area on my roof that needs attention and that will most likely be a winter project this year.
Like Sam advised, try the local rv dealer or give JR Repair a call if you would like the original metal at 419-883-3001.
2016 Toyota tacoma TRD sport
Classic 2693 RD