Cutter Ruler
thingiverse
Meanwhile improved versions are available at https://www.thingiverse.com/thing:3099863 and https://www.thingiverse.com/thing:3103154. This adjustable ruler allows dragging a cutter knife along a border in a precise distance. The ruler is printed as two parts that need to be glued together with CA glue to save support material. Glue an M3x12 threaded rod into the slider, and insert a M3 nut into the fixing knob. Some pressure or a pre-heated nut will be required for insertion, but then it will be securely fixed.
With this file you will be able to print Cutter Ruler with your 3D printer. Click on the button and save the file on your computer to work, edit or customize your design. You can also find more 3D designs for printers on Cutter Ruler.