There may come a time when you need to undo a nut and just don’t have the spanner or socket to do it with.
Enter the spanner bolt!
Simple to make and is not what some people call a “novelty item”.
This one actually works.
Take a 6 inch 8mm bolt, two nuts, and two nice thick ‘penny washers’.
File down the washers as shown and you’ll end up with this:-
OK, it’ll never be as good as the proper thing yet it has its uses, especially on those “custom sized” nuts.