The wing on the Mayhem is a constant cord wing all a person needs is one rib to obtain them all the belly pan is then made to fit and the wing tips can be of your own design. But the originals wouldn't be hard to make.
The fuse is more or less just a box with a turtle deck, fairly basic stuff in my book. That's another reason that I don't discard anything from a wrecked plane.
Some times I even make templates of everything before I start to build it.
The cowling might can be bought thru fiberglass specialties I don't know. But again a person can make that from wood aslo if push come to shove