How to solidify irregular object in Geometry Nodes

Question

How to solidify irregular object in Geometry Nodes

I created a spiral like object in geometry nodes but how can I make it a solid object? The fill curve node doesn't work. (mesh to curve - fill curve - curve to mesh)

By solid I mean like this:

It's going to be 3D printed so it has to be solid / Manifold

I know I could apply the Geometry nodes modifier and fill the faces in by hand but I'm using Geometry Nodes to make it procedurally (I'm going to be 3D printing out different amounts, sizes, and shape of arms to test with).

See attached file below:

Answer 1

You can separate the bottom outline (using Position$—Z=0$), turn it into a Curve, then Fill Curve; you just need to make sure you Merge By Distance first (and at the end):

Answer 2

Here is one part of the solution:

so you get this:

i improved it a bit:

result now:

Two disadvantages:

1. my mesh to close the ends is just "one" polygon
2. the angles of my "closing" are not perfect like here:

but maybe you know better to solve that than i do ;)

i changed this to "community wiki" so whoever wants can extend this answer ;)