I love this forum! You guys rock. I've said it before, I'll say it again. YOU. ROCK. I bought a sheet of control horns from FT. Seemed like a good idea, and it was, really. I'm going to need them and it pushed my order into free shipping.
You all just made me realize something. It really just clicked in my head. A control horn is just a lever that the servo connects to, to move a surface. It really doesn't matter what it's made of, or even it's shape really. It needs to have a hole that's not going to expand quickly with use, it's got to be long enough to move the surface it's attached to, and it needs to be cut so that parts of it can be glued into the foamboard. That's pretty much it. Keep it light, keep it strong and have tabs so it can be glued.
The angle of the rod to the surface is of obvious importance. A higher inclination would mean more throw. Stick to about where the plane was designed with the FT control horns and you've got it. Dremel off a slice of laminated plywood. Cut out a piece of the plastic housing from an old DVD player. Given a Dremel ( or the like) the possibilities are endless.
I love you guys!