This loop must be fairly quick and easy to tie and - here's the unusual bit - I want it to be as difficult to undo as possible.
The most difficult to undo knot I had ever come across , is the "Oyster" bend ( M. B 5 ). When tightened, it becomes a rigid sphere, that is awfully difficult to untie ! Try it as a loop knot, it might suit to your purpose. ( See the attached pictures ).
I just tied a loop knot with the oyster bend. I like it. Very secure and good looking too. This might even make a good lanyard knot.
