This is my last animatronic project, an Animatronic Tail controlled by an Arduino Nano and two Standard Servo.
The tail itself is made by hand machined nylon discs, for the first version, and laser cut acrylic discs for the final version. All the control cables are standard steel cables, using a soft steel spring as connector for the vertebrae.
To drive the servos without drain to much power from the Arduino i used a 6V LiPo BEC, usually used with RC Models.
I think that the pictures will explain better than a thousand words:
And the video too: