A typical hobby animatronic uses servos. So naturally your control system may only have the ability to control the typical RC servo PWM signal. But what if you have other things like LEDs or motors or…. Or perhaps some pixels. I needed to control some relays from a servo signal and while I know you can purchase such things, I rolled my own with parts that I had on hand. I used a Arduino NANO clone and a 2 relay module. This lets me control each relay separately using two of the servo control channels. I used a carrier board for my build but you could make yours a lot smaller if you just solder the wires directly to the NANO and cover it with heat shrink. The circuit is power from the +5V servo power.
While I was working on this I also had the need for controlling some eye LEDs. I wanted to have adjustable colors for these LEDs so I could have used some RGB LEDs but this would have taken 3 control channels (one for each of the 3 colors) and would require some sort of driver for multiple LEDs. Then I thought about using addressable LEDs, a NeoPixel ring was ideal for lighting up the project that I was dealing with. And it would only need 2 control channels. I again used a NANO and cobbled some code together that lets one servo channel control the brightness and another channel to control the LED color color (all LEDs show the same color). Again I didn`t need to worry about size and it is powered from the +5V servo power.
For more information including wiring diagrams and the Arduino code go to my Servo Project page.