This is a set of 4 x 10cm "rulers" or measures, for inserting into the vertical railing of a CR-10 printer. The idea is that you can see the height of your print and thus estimate how far to go. I remixed an existing rail insert, linked here. The STL file has 4 separate parts - for up to 40cm of measure. I suggest you set "0" to the same level as the print bed, and then print blank insert for above/below the rulers. Use your slicer to stretch the blank inserts to the appropriate height.
I used OpenSCAD. Imported the original model, and added the text and lines. Easy as.