I needed to mount individual servos for each aileron in a nearly completed wing, after realizing that my original plan of a single servo via torque rods was not going to work due to a lack of space. The photographs should help illustrate their intended use:
They are installed at the intersection of spar and rib, adhered with hot glue. I used the carrier block as the template for the initial hole, cut into center section sheeting.
1.)Slide the servo into the carrier block, using foam rubber or double-sided tape to shim the servo out flush with the open face. If you elect to not use adhesive tape, the lid will hold it securely and future swaps will be easier. (My planes don’t outlast servos.)
2.)The wires exit through the slot, THEN route through the wing. The design is ambidextrous, so mirroring parts should be unnecessary.
3.)Attach the lid. Apply a healthy bead of HOT glue to the spar and rib. Quickly, grasping the assembly by the lid, slide it into place. The carrier block will smear the glue into a large face joint, and the lid will locate the carrier block flush with the sheeting. After the glue cools, (balsa and PLA make an incredible bond using hot glue!) the lid can be removed, and access hole made final size to correspond to the horn slot in the lid. I usually omit horn securing screws. If you must have them, plan accordingly!
Lid and carrier block are 20 grams. I print this in PLA with 15% infill. The .stl files should already be properly oriented, but the lid is printed face down (locating blisters up,) and the carrier block is printed so that the open face and screw holes are facing up. 2.5mm screws or small wood screws (like the ones that come with the servos for mounting on plywood rails) hold the lid to the block.