WINSTON FREER TILE PUZZLE
The DADDY of all the geometric puzzles!
There are a few different versions out there but take a look at the video below to see why this is the best
https://vimeo.com/martinduffy/winston 
 
See Jason England’s great presentation here
https://youtu.be/Qjx1-Ujlk1s
 
See my friend Alain Nu with his Puzzle of Life presentation here
https://youtu.be/fW732OHxAQs