Summary

I printed the robot 2x scale, and my son wanted "articulating" arms, so I modified modified the arms and hands with popcorn connectors.

The body - I will upload later. For my "already" printed body, I printed a pinion and glued it in the holes.

The popcorn connectors come from PopCorn Joint - https://www.thingiverse.com/thing:194240

I have supplied the SketchUp (2016) file also.