How to Make a Polygon With Pressure Information

I wanted to make a polygon, like input points are a line. Like something that has an envelope around that line and have that envelope be thicker or thinner. The way they would do it is kind of take the users input points, turn them into a spline,. And then draw lines between each point on that spline. So more pressure is a thicker line, less pressure is a thinner line. It just does not look good. I spent like the next six months, if not longer working on this variable with line that was fast enough that I could use it while drawing but stable enough so that the line didn't change behind your cursor. You can now dial in settings for how