Steel rod knot.
https://diqn32j8nouaz.cloudfront.net/steel_rod_knot.jpg
Previously:
https://www.homemadetools.net/forum/...476#post158604
https://www.homemadetools.net/forum/...313#post158013
https://www.homemadetools.net/forum/...645#post163045
https://www.homemadetools.net/forum/...220#post145920
https://www.homemadetools.net/forum/...431#post154707
