How to make simple homopolar motor ‚race cars‘ | The Kid Should See This https://thekidshouldseethis.com/post/how-to-make-simple-homopolar-motor-race-cars
race track‘ of tinfoil, attach two round neodymium magnets – an AA battery x2 (or more) — the polarity of the magnets
If you have two different sizes of magnet on each end