I know you can have an externally butted tube, however it would be really nice to be able to show the ST sleeve many of us use on our frames.
http://static1.squarespace.com/static/53d96c09e4b080c1a403b5a7/53e6d7c7e4b0cc1fd4cb8637/55ef8d94e4b085756a63e97f/1441762709301/Final5s.jpg
and of course being able to make it scalloped would be the bees knees!
Seat tube sleeves
Thanks for the suggestion. I will keep that in mind for a future update.