Beer head measuring tool.
https://s3-us-west-1.amazonaws.com/h...uring_tool.jpg
Previously:
https://www.homemadetools.net/forum/...618#post123375
https://www.homemadetools.net/forum/...054#post137980
https://www.homemadetools.net/forum/...3095#post98045
https://www.homemadetools.net/forum/...5062#post81114
https://www.homemadetools.net/forum/...947#post152927