I thought I would try one. Very simple. The only thing to do on the bottom half is insert the refill and screw on the tip. The cap end is simple enough. Turn blank to size and press in parts. I found these parts are on the tight side. One of my blanks shattered, even after chamfering and cleaning out the tube a bit. Check out the pics.
I like the carbon fiber touch. I've done three SA's so far and have had mixed reviews from family members. The gals all hate the feel of the pen because they're gripping an open spring. The guys all love it and could care less how it feels in the hand. Go figure.
As for the tight fit on the hardware and the cracked blanks, is it possible you used a carbon fiber blank meant for a Sierra? I ask this, because I almost did the same. At first glance, with the instructions calling for a 27/64" bit, one might assume the pen tube of the SA was the same as a Sierra. There is no mention of tube size in the instructions to make you think any differently.
Then I looked at the catalog and saw that PSI lists the pen as 11mm, with an 11mm bit recommended. I pulled out the calipers and started taking some measurements. Guess what? The kit tube is bigger than the Sierra tube. Not much, but still a tad bigger. Just for the heck of it I pulled the cap hardware off a finished SA and tried it on a spare Sierra tube. Real tight fit, as you mentioned. From the amount the tube expanded, I can see where a blank might crack. Sort of a shame, as I wanted to try the next batch with a longer upper barrel so I could add a clip.