IMPORTANT This ruler works differently. Each line does not mark a millimeter, the EDGE of the line does.

It is 250 mm (9.84 in) long, and only measures in metric units. I have designed & printed this and it works well. Hope you have good luck with it too.

For a flexible version, make the Z-axis 50% in your slicer

Total dimensions:
250 x 20 x 2.2mm