We are very lucky to have several excellent sources for component structures, wings etc.
In addition to the fine work done by Crist, we also have the guy who perfected foam wings for the modeling world: Bob Hunt. Bob has been making excellent foam wings for so long I think he made one for my grandfather, and I'm retired!

.... His wings are perfect for our needs, and they come with his helium impregnated foam and balsa. They are really light!
Bob's "How to" videos are also very helpful. I have learned a great deal from them.
You can go here on this forum for more info: Vendors Corner > Robin's View Productions