Enhanced 'Servo Button' for various designs with servos and servo brackets (e.g. http://www.thingiverse.com/thing:5784). Instead of glueing the button to the servo one can now screw it onto it.

Print it. Scale is in mm. Due to ABS shrinkage I had to upscale my model slightly. YMMV.
Remove the lid of the servo (back side) and put a hole through it.
Insert the nut into the servo button, attach the button to the lid with the screw, put back lid. Use an 'M3'-type screw with a length of about 10mm.
Make sure the head of the screw doesn't touch anything electrical inside Your servo. If in doubt, add some isolation.