As I wrote in Chopstick Junior 1.0 (there you can see it in the robot) here comes the part with the Arduino Nano on a PCB.
Why I did this?
Well, it's just a try to use the Arduino Nano for other robots too. This gives me the chance to remove the MC and put it in another robot or just upgrade this one with a new Nano. But the most important is that I can connect all the servos I need directly to the board without any solering or using male-to-female cables.