Great looking pen. How did you go about the finial?
The finial assembles on the finial coupler just like the kit finial.
I noticed that the finial threads matched the cigar kit finial threads, and as I have left over cigar parts, I used a cigar finial for threads - just in case I screwed up I didn't loose a kit part.
I chucked a cigar lit activator tube into my collet chuck, screwed on the cigar finial, and turned it down to make a threaded insert. I then chucked up the blank and drilled a hole in end for the insert. I epoxied the insert in on the lathe to ensure good alignment - I chucked the cigar activator in my drill chuck on the tail stock, screwed on the insert and pressed it in. Let it sit on the lathe until epoxy sets. Be careful not to epoxy the new insert to the cigar activator.
Lastly re-chuck the activator to hold the finial for turning. I stopped and loosened/tightened the finial every so often while turning to be sure it didn't get too tight to remove.