I am convinced this puzzle is not possible, yet it is not easy to prove. It seems, by analogy with another puzzle, that if the board can't pass into a metal ring, it can't be solved.
Description:
- A wooden board with 4 holes in which the wooden balls can't pass
- A string with a wooden ball at each end
- two twisted metal rings in which the wooden balls can't pass
Goal:
to remove the metal twisted rings

