Beautiful Thuya Burl, Kitless Pen Thomas.
Glorious Clip. Magnificent Blank, Excellent Closed End Construction.
IMHO, I do not know if there was an Internal Constraint that prevented you from Turning the Cap to the Diameters of the Cap End and Clip Ring dimensions. As it looks a little Oversize at the Transition Points.
Excellent Proportions, and Finish.
Congratulations,
Brian.