Now this is cute:

https://www.youtube.com/watch?v=tQTU4hzE4dQ#ws

But can you explain how it works?

its a homopolar motor in learner fashion... EZAy and yes Cute!

but he allays uploads others videos and never links back or gives credit. it bothers me... you should find the source and re post it...

~Russ

its a start... http://en.rocketnews24.com/2014/12/02/worlds-simplest-build-it-yourself-toy-train-set-may-also-be-the-cleverest-with-just-three-parts/

https://www.youtube.com/watch?v=J9b0J29OzAU#ws

i feel better... ~Russ