Ed I rarely comment on plastic pens and when I do I usually don't have anything nice to say about them, that is my specific reason for trying not to comment on them
However I do want to give you some encouragement, beauty is very much in the eye of the beholder and my perception is: It doesn't matter how thin or fat you make it or what shape you choose to make it.
If it is how you want it to look then you have achieved your objective, I have seen some downright awful materials, colours and shapes on pens but others love them so we are all different.
For me these pens don't fall into that category, I am looking at the fit and finish. If you can get the sizing right at the bushes you will have a well fitting pen regardless of what is between that, if you can avoid trackmarks and achieve a smooth finish you will have a nice looking pen that feels good to hold whether it shines or not is up to the creator.
You have achieved these results admirably. I like Marmite but I don't favour the Polaris, I agree with Neil's comments that it looks like something to be inserted where the sun don't shine.
I think you have done a fine job on these pens and should keep heart there is nothing wrong with a fat pen.
I also agree with the comment that Neil said regarding the shape of the Sierra pen ... 
