Microscope calibration tool.
Fullsize image: https://diqn32j8nouaz.cloudfront.net...l_fullsize.jpg
https://diqn32j8nouaz.cloudfront.net...ation_tool.jpg
Previously:
https://www.homemadetools.net/forum/...588#post166849
https://www.homemadetools.net/forum/...368#post158236
https://www.homemadetools.net/forum/...291#post150307
https://www.homemadetools.net/forum/...516#post158794
https://www.homemadetools.net/forum/...291#post150307
https://www.homemadetools.net/forum/...298#post161591
