Even a blind squirrel finds a nut. This is one I cast and now I wish I took notes on what I did. The whole pen is tapered from about 15 mm to 12 mm. The buttons on the ends are made from the scraps from the opposite end of the blank. I've. been making a lot of rollerballs because I like the more practical aspect of them. This one came about because a coworker helped me with a particularly tedious project and she was a tremendous help. I'm a bit worried that "wife's prerogative" may come up and I'll have to make another one.