Vintage German line bore measuring device.
Fullsize image: https://diqn32j8nouaz.cloudfront.net...e_fullsize.jpg
https://diqn32j8nouaz.cloudfront.net...ing_device.jpg
Previously:
https://www.homemadetools.net/forum/...153#post141491
https://www.homemadetools.net/forum/...061#post141008
https://www.homemadetools.net/forum/...906#post140565
https://www.homemadetools.net/forum/...357#post142381
https://www.homemadetools.net/forum/...726#post139978
https://www.homemadetools.net/forum/...745#post140022
https://www.homemadetools.net/forum/...959#post137591
https://www.homemadetools.net/forum/...374#post116664
