Plumb bob. By High Caliber Craftsman. 7:30 video:
https://www.youtube.com/watch?v=PHlBRbrKcpw
Previously:
https://www.homemadetools.net/forum/...612#post170455
https://www.homemadetools.net/forum/...929#post179515
https://www.homemadetools.net/forum/...629#post178225
https://www.homemadetools.net/forum/...273#post176971
https://www.homemadetools.net/forum/...271#post172852
https://www.homemadetools.net/forum/...629#post170493
https://www.homemadetools.net/forum/...599#post170413
https://www.homemadetools.net/forum/...326#post169442