Hi andras - do you mean writing only objects that are not currently hidden to a file?

That is possible with the Export command off the File menu, which is the shortened name for "Export selected objects".

Save As will save the entire file including hidden objects to a 3DM file, but Export will only write the objects that you have selected to a 3DM file.

Since hidden objects cannot be selected, you can just do a "Select All" (Ctrl+A) before doing the export, to generate a 3DM file that does not have the hidden objects written to it.

- Michael