How to create separate non-overlapping surfaces from many polylines

Hi Folks,
I’m in my first ten hours learning Grasshopper and following this tutorial:
I’ve included their example file here.

As an extra step I want to extrude all the individual shapes within this design to a point slightly above the centroid of each shape.

I understand I need to do something like the following, though I don’t know exactly how to do it or what components to use:

Combine all the different polylines into one set.
Create separate non-overlapping surfaces for all the closed areas.
Find the centroid for each surface
Create a point a given height above each centroid
Do some kind of tapered extrude (loft, sweep?) to that point.

I’ve spent about an hour trying to figure out how to combine all these polylines and turn them into separate non-overlapping surfaces without any luck. Would appreciate any help. (185.5 KB)

Most of that was already done since you had a split surface. (184.9 KB)

Here’s a variation on the same idea where the height is proportional to area of each surface (edge curve) extruded, with sliders for ‘Min/Max’ heights: (187.4 KB)

Perfect. Appreciate the fast reply.