Here's all the neat stuff that you can do with Symmetry rulers in Manga Studio/Clip Studio Paint.
There is no dialogue. Just visual demonstration, and nice music.
It may seem like a novelty, but symmetry rulers can make certain tasks much easier. Need to make a playing card? A ritual magic circle? An evenly spaced pie chart? A shuriken? A buzz saw blade? A hypnotic effect?
Or maybe you just wanna mess around with it like a high-tech spirograph, or interactive kaleidoscope. Don't dismiss the symmetry ruler as a simple novelty.
https://www.youtube.com/watch?v=Y28c-mv_iXU