Slowly but surely, about 3 hours work now.
Marked out, ready to cut out and pare back.
After lots of deliberation which amounted to simply an
aesthetic / functional consideration,
I went with the user - a strip of Lignum Vitae!
(considered using an end grain piece but...
it chipped due to the short end grain...)
Glued up, almost considering keeping the octagonal section...
But then again maybe not!