Tips on fixing 0-width CSG slices?

I use 2 techniques:

  • I drag the disconnected parts onto the main part (it’s a good practice to fix the position of that main part first), so it sticks to it’s surface. This will (in most cases) get rid of tiny space between them.

  • I fix parts’ positions

But as Defaultio already mentioned, it’s best to sculpt a shape out of one, main part.

And btw, this isn’t exclusive to CSGv2. Switching to v1 can’t affect this issue.