I am working on the flaps now and I told you I would do a hinge detail .

First cut and sand to this shape 7 ply 1/8 AC plywood and drill a hole for the bushing. Next cut a slot into the flap the same thickness as the flap in this case 3/8. Then 1/2 inch each side recess 1/2 the thickness of the flap in this case 3/16. this is the hinge pocket and balsa will be epoxy will hold the LE cap and sanded to the shape of the LE of the flap. Do a test piece first to get the depths before doing in on your flap or elevator. I hope this explains it.

Easy to do hard to write about.