How to create a surface by offsetting lines


I am wondering if it is possible to place long polylines and change the width of those lines at each position to fill the area where the lines meet.

For example, using Kangaroo, I believe I can fill it by using “collider component” and some size circle as shown in the picture, and then extracting the radius of the circle.
However, I can’t set it up well in “colider component”, so I am considering other methods. Does anyone know of any better way to do this?

If you have tried K2, you can share the failed attempt. So people can start from there.