I recommend that you put the newly created geometry inside a 'group.entities' container.
Then you can ask if the user wants to smooth the extrusion [it already is!] and explode the group etc...
It's easy made with a @gp=@ent.add_group() and @gents=@gp.entities references...
I am getting mixed results too... also and the start/end labels are not [always] vanishing on the 'exit'; you have given them a @ reference so just have all of your 'endings' methods use @ent.erase_entities(@start_label,@end_label) etc...
