I know i am kicking a thread that is almost 4 years old...but this would be very helpful. I have no idea how to write plugins/extensions for SketchUp, but it seems to me that all we need is any time any geometry is drawn that is not already part of a group, it should automatically become a group once it is a solid. This would not get in the way of drawing the way we already do...and once you have a 3-d solid it would group itself. That group could then be converted to a component or edited to expand the shape further (but at least for me 98% of the time i group each solid separately and put my groups together to form larger shapes...rather than making complex single shapes).

Does anyone know how to create a plugin that could do this? I have looked for something like this on-and-off for several years with no success.