The bannana wraps as they are called can be handled 2 diffrent ways. On the sides it is just flat sheet aluminum. The front and rear corners are a diffrent story. Those will require purchase of new ones from an Airstream dealer or a very talented sheet metal guy. I belive Airstream stamps those to make the compound curves. You may want to start by calling a local dealer for pricing and availability then see if a local craftsman can make them for less. Good Luck, and Welcome to the forum!
WBCCI #5501 AIR # 49
1978 Argosy 28 foot Motorhome
Wise men talk because they have something to say; fools, because they have to say something. -- Plato