A Set square or triangle is an object used in engineering and technical drawing, with the aim of providing a straightedge at a right angle or other particular planar angle to a baseline. The simplest form of set square is a triangular piece of transparent plastic with the centre removed. One has an angle of 45 degrees and the other 30/60 degree angles. The 45 degree set square also has a 90 degree angle.
The French curve is a template usually made from plastic composed of many different segments of the Euler spiral. It is used in manual drafting and in design to draw smooth curves of varying radii.
