Hat stretching tool.
Fullsize image: https://s3-us-west-1.amazonaws.com/h...l_fullsize.jpg
https://s3-us-west-1.amazonaws.com/h...ching_tool.jpg
Previously:
https://www.homemadetools.net/forum/...081#post120595
https://www.homemadetools.net/forum/...1278#post74097
https://www.homemadetools.net/forum/...444#post139046
https://www.homemadetools.net/forum/...308#post138803