Sheetmetal brake. By The Metalist. 16:44 video:
https://www.youtube.com/watch?v=OrtSrrPzWKg
Previously:
Metal Brake Build Guide
https://www.homemadetools.net/forum/...462#post177691
https://www.homemadetools.net/forum/...981#post175933
https://www.homemadetools.net/forum/...743#post170866
