ECG ruler.
https://diqn32j8nouaz.cloudfront.net...1_fullsize.jpg
https://diqn32j8nouaz.cloudfront.net...r_fullsize.jpg
Previously:
https://www.homemadetools.net/forum/...279#post214936
https://www.homemadetools.net/forum/...459#post212050
https://www.homemadetools.net/forum/...452#post122472
https://www.homemadetools.net/forum/...756#post206272
https://www.homemadetools.net/forum/...601#post205653
