I tested differant types of thin plywood laminated on balsa . I did this about two times before i was happy with the stiffness and little flex .

Then I used robart hindges burried in balsa blocks that were later sanded down .
The flaps function great .Considering I was working with a finished wing the bigggest challenge was keeping the top -non moving part of the wing/flap in place and sturdy while I was tinkering with the bottom part .

Did you notice the rail in the fuse , the canopy will slide .
Its a simple square stock of aluminum with a straight line cut in it. Then I added ball links to the inside canapy that will slide thru the rail manually .