1:2 multiplier for standard sized RC servo. My purpose was to get more speed from a cotinuous rotation servo, but it can be used also to get twice as much angle (for example to get 360 from a 180 degree servo for a pan-tilt unit).
In most standard servos there is no need to install the spacers, but some like the MG995 need them.
Use one M3x15mm cross flat head screw, two M3 washers and a M3 self locking nut.
See it in action here: https://youtu.be/DglwlFt9taQ
Edit (2-apr-2016): As there is demand for a micro servo version, I've made and uploaded the corresponding models with the suffix "_micro" (note I haven't printed/tested these).
If you are a curious maker / "tinker" / hacker, have a look at my blog: