If the shapes were spherical or even capsules, then all this would be easy peasy. However, since we are talking about custom shapes and according to the above drawing, the area width (distance between the max and min areas) is variable across the perimeter, I would personally go with discrete, instead of continous values.
For discrete values, it takes just a couple of minutes to setup everything. It’s a question of creating a static mesh component with the custom shape you want. Then add this component, as many as the zones you want to the item. And finally binding the overlap events:
](filedata/fetch?id=1807459&d=1599049558) ](filedata/fetch?id=1807460&d=1599049563)
For continous values, that would require playing with collisions, traces and all, and right now I don’t have time to play with all that. Unless the width is constant and known, which in that case, it’s quite easy. You tell me.