35 years ago I built 3 Byron F-16 and one F-86 models. They used a torque rod buried in the leading edge of the wing control surfaces that mated with a molded bellcrank in the fuse-wing root when the wings were bolted on. It was hidden, fairly simple and I never had any problems with it. I have never seen any other manufacturer use this method. Maybe it is patented, but patent rights have never stopped certain far east companies from copying what ever they wanted.