Ruler 20mm

Metric ruler with steps of 1 mm. Measures up to 20cm.
Best print with a layer height of <= 0.1 mm.
See also other versions of the rule:
Ruler 15mm:
https://www.thingiverse.com/thing:3519226
Ruler 15mm with hand held place:
https://www.thingiverse.com/thing:3518248