Fair warning on the advice above. As you shorten the surface arm, you increase the stress on the hinges.
Most 3D airframes, high rate surface deflection will be sufficient with a 1:1 ratio (servo arm=surface horn length).
Servos have usually 90-100 degrees of travel. That's usually enough for surface deflection for 3D.

Here's what I mean illustrated.
The bottom example will put more stress on the hinges than the top even though the 1:1 ratio and amount of deflection is maintained.