Nice one, Dave.
I have a couple suggestions that might help you take the next one to a higher level.
The stem looks nice and thin (good work!), but so does the button. This can be a difficult balancing act - how thin to take the button for comfort, and yet leave enough to support the thin stem and give something to wrap your teeth around. Since we're making stems thinner and thinner these days, there's a real danger of splitting one if the button isn't big enough. Take a look at the saucer Rad just posted:
viewtopic.php?t=2973&start=0
And take a look at the size of his button. That's basically the size you want to shoot for.
Personally, I would like to the round portion of the stem slightly larger in diameter. This part walks the line between subjective and "what is right" about a pipe. I actually didn't notice it at first, and only when I really started looking did it hit me. Again, see Rad's pipe.
I like the shank end cap. The diameter looks a little lare, but I think that's only because I think the stem should be larger diameter. This s not a huge problem though, and again I didn't really see it at first. I just noticed that it's actually acrylic - that must have been a pain to shape. Kudos for grabbing something unusual to try.
One thing I notice is that this pipe is *huge*. Well, by my standards anyway. I'll bet it could be smoked all day on one load of flake tobacco.
Overall, I think it's a good pipe. You're definitely getting the hang of this.