This is more complicated than it sounds. A Rhino document can have both layers and blocks, as can a STEP file. If a file contains both, there could be a problem. A script like @pascal wrote for changing blocks to layers wouldn’t really work here since it would change your 3dm data to something you don’t want. I guess you could undo that after exporting but that shouldn’t be necessary. I need to think about this some more.
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