When doing a sweep with a closed curve, it seems the closed sweep should be the default setting.
Hmm, in Windows Rhino in any case, if the rail is closed, there is no other choice, “Closed sweep” is checked by default and can’t be changed. Are you saying on Mac Rhino this is not the case? Can you post an example file?
Here’s a three circle example:
Yeah, it’s a coin flip, but you’re right, in this case I would bet that most people would indeed want a closed sweep…