Great use of parts. The work on the clip is very nice.
Only think I may have done differently is to have increased the difference in diameter in the upper and lower parts of the pen. It looks like they're similar, but not exactly the same. I think when it's a little more obvious, it comes across as more intentional. As it looks now, it's so darn close it looks almost like one of the two is slightly off center.
I'd say once you nail that, you'd have a real winner. Less kit is more a lot of times, I'd love to see more pens made like this.