The components needed are a body, two wheels, motors to drive those wheels and some electronics. [Limenitis] demonstrates the design process in the video below (in Turkish, with English subtitles ...

Getting a robot to stand on two wheels without tipping over involves a challenging dance with the laws of physics. Self-balancing robots ... shows how to make one with just a few common components ...

That thing, in this case, was the RYNO — a $5,300 one-wheeled, self-balancing electric motorcycle. (The term "unicycle" is not welcome here.) The idea for the RYNO was born seven years ago ...