I have a few extra bamboo ferrule blanks available. They are about 18.3 mm in dia and approx 1.22 inches long. $1.25 each or 4 for $4.00 + S&H. Once they have been installed they need to be sealed. I use thin CA.
A dab of linseed oil on a rag and smooth it out, then while it's still wet hit it with thin CA in the same manner. <~ with work piece under power/spinning. When the two come together they have a chemistry that's really neat and will provide a durable and shiny finish.
I have a few spare solid bamboo ferrules blanks if anyone is in need.
WOW! What a smooth hit!