Enter the 'Shirt Pocket' style fountain pen. I made this one to be short enough capped to fit in my pocket easily, yet when posted (even unposted), it is the perfect size for long writing sessions.
This particular pen was made out of some really cool striated green ebonite that I have been dying to use, and so is made with flat ends to show off the ebonite cross-sectional patterns, but of course it could as easily be made with rounded, 'torpedo' ends.
In any case, this was the first 'just because I wanted to' fountain pen that I have made in a while. Loved the experience!