Cannot join curves

This is driving me crazy. This series of curves was created from the edge of joined surfaces. I want to use it to create a sweep but I cannot join the curves.Test.3dm (34.7 KB)

Any help would be appreciated.

Hello - some curves are doubled up and joined on themselves, making closed curves.
Explode, SelDup, `Delete’, then Join the rest. Can you post the surfaces the curves are from?


Thanks that worked. I found that the joined surface that I used also had duplicate surfaces.