Modal logic ruler

**This is made for use with a normal pencil** and works great with one.

I've tried it with a mechanical pencil and it worked fine-ish but the spaces were a little too wide. It doesn't work at all with a ballpoint pen, at least in my experience.

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# Background

A very minimal ruler I made for my modal logic class. It can either make a modal double scope line for possibility elimination and modal impl intro. Or you can just use the box and first line for a quick nec intro. Finally the single vertical and horizontal line by themselves can make a non-modal assumption scope.

During the course one of the most repeated patterns I ended up drawing was the double modal scope line. It take quite a lot of movements to draw it right, first you have to move the ruler a little away, but not too far away from the first line, then you have to draw the horizontal line. All these steps add up if you're writing a test or just want to draw them neatly over and over again, in quick way!