This is a little converter from a standard size servo (6 mm diameter) to male Lego cross axle. I intentionally designed the servo hole to be just a tad small to
...さらに表示 ensure a tight fit. You may need to sand it out just a bit to get it to fit. The Lego axle should fit like a glove.
The photo shows the part in use with a Futaba S3003 servo to make a servo winch for my Axial Wraith Spawn.
The winch fairlead is from here: https://www.thingiverse.com/thing:2438136
The hook is from here: https://www.thingiverse.com/thing:14653
Solidworks files are included if you want to make any changes. Enjoy!