How to fill an extruded curve from a double sided offset

Hello! I’ve managed to offset and join curves to both sides of my original curve and extrude them out. Now I have 3 extrusions but whenever I cap them it simply caps the whole block. I’d like to make them join similar to the one that’s sitting on the face of the ring. The one on the face works fine but it’s too thin to print so I need to make a thicker version at least .25mm thick.

Thank you in advance!
Whale Signet.3dm (1.2 MB) Whale Signet.3dm (1.2 MB)

Hello - you need one more round of clean-up on the curves:

then it will work.
image

I think I’d be inclined to clean up a bit more even - round some hard corners and smooth some of the lumps -

-Pascal