Thank you, folks! As usual, make a post here = learn tons of new stuff. Like most of you, I have lots of scrap/cut ends in my shop, so I can try cutting out the liner. I can also try housing itself. I can also source some plastic from my LBS. They sell those fancy Tarmacs. Lots of options. Now that I think of it, I believe I have seen that narrow plastic tubing at a friend's house who has an elaborate air compressor setup for painting/airbrushing. I'll try to report back.
@
CliffordK, many thanks for your kind offer of sending some tubing. I'll shoot you a PM if I can't source locally. Otherwise, I'd like to save you the trouble! Thanks also to @
JohnDThomson and @
MichaelAngelo for the helpful links, and to @
SJX426 for the cool Colnago BB photo.
And @
RobbieTunes, always good to hear from my NC pal who hands out free derailleurs!
One short post to C&V, and I have tons of options. Thanks again!