A 200 mm ruler that can be used for filament shrinkage calibration, or just for fun.
There are two versions of this ruler one with flush lines and numbers and another with embossed lines and numbers. I have the ruler, lines, and numbers as separate files to make it easy to print them in different colors if you wish. The STEP files have all three parts combined but should still show up as individual models in the slicer.
For this to be accurate you need to make sure to account for shrinkage of the filament you are using. I used this to help calibrate the shrinkage amount for my filament as I have a 150mm ruler that I can compare it to.
Also, you should set the line width to .25 for the lines and text, or better yet use a 0.2mm nozzle if you have one.