Squaring Up Ruler
thingiverse
My wife needed a squaring up ruler for cutting quilt blocks and I thought I would have a go designing and printing one. I've uploaded STL files for 6 and 7 inch (the largest that my printer can support) rulers, but the design can be customized in OpenSCAD to be as large or small as you need or to use metric measurements, if you live in a civilized part of the world. By default, the ruler is pretty thick. It might work better to configure it to be thinner, but then you risk cutting into it when you cut your fabric. I printed mine in PLA and was able to get good results using transparent filament for the body and then switching to black for the markings.
With this file you will be able to print Squaring Up 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 Squaring Up Ruler.