Not Solid, just a "Joined Surface

 From:  Michael Gibson
5786.11 In reply to 5786.9 
Hi Bill,

> Has anyone tried the 3dm import function from Rhino to Solidworks
> on MOI 3dm files? Is this an option, because this is what I am trying
> to achieve by exporting to STEP.

Yeah, that's definitely worth trying - I'd recommend trying all of STEP, 3DM and IGES as well to see if one of those works better for your particular case.

Also it's very normal for IGES files to contain individual surfaces in them so most likely SolidWorks will go through a joining process itself if you use that format to transfer stuff over.

- Michael