Simple but essential tool for architecture, geometry, drawing and any form of other arts. It is logical to make this with 3d printing, because of the cartesian coordinate system of printing machines theorically must give the perfect 90 degree angle. If it cannot, it is good calibration tool for your machine.

Note: You can add stickers or drawings for measuring (cm, mm, inch, etc.). Little texts are not good for 3d printing in my opinion.

I recommend 1 mm nozzle for this printing.