Because the pen goes from 14mm right down to 9mm I will post a photo of them latter
The old Craft supplies in Millers Dale used to sell these kits years ago
I have one of those ready and waiting for me to make. I bought it over 20 years ago to make the wife a pen.
I take one look at the stepped tube and put it back in the box for next time.
Used to love the old Craft supplies, was well worth a run out to visit.