Combination lock from bolts. 20:35 video:
https://www.youtube.com/watch?v=_doRXEfVL9Q
Previously:
https://www.homemadetools.net/forum/...708#post174701
https://www.homemadetools.net/forum/...643#post178295
https://www.homemadetools.net/forum/...081#post164892
https://www.homemadetools.net/forum/...360#post146438
https://www.homemadetools.net/forum/...923#post119782
https://www.homemadetools.net/forum/...990#post100427
https://www.homemadetools.net/forum/...519#post135921
https://www.homemadetools.net/forum/...037#post129872