Knurling device. By Family DIY. 8:00 video:
https://www.youtube.com/watch?v=L-onTIKfLQc
Previously:
https://www.homemadetools.net/forum/...972#post140771
https://www.homemadetools.net/forum/...002#post100474
https://www.homemadetools.net/forum/...016#post171914
