Go Labs Mighty Motor EDU-3040
Vendor's Description:
The Go Labs Mighty Motor kit lets you build a DC motor and use it to propel the included boat. Wind your own armature coils and position magnets to explore the link between electricity and magnetism, and its practical application in DC motors.



Tried that when I was a little kid.
Good kit for little kids though but for me, the shaft rusted, boat styrofoam body got crushed, the entire thing short circuited because of the water damage and battery leaked.
Not a very nice ending, eh?
So, yeah... This is a great kit.
Not for me or many other hobbyists who already know what a motor does or how it works though.