about rear up exahust alum panels, in my plane, i used real aluminum one by one cuted make the scale shape, and make a carbon fiber at the bottom ,
all glued with epoxy. see , are one by one, if you see full size, they are all differents, like thisuu
at the final exausht also are aluminum , in this case .... lot of work, see 3d printer helmet, and scale wheel, iff you need it.
gus