I sell ,many of these. And while the double barrel takes longer (esp if TBC), and there's a tendon-like fit on the upper end of the lower barrel, you can actually make these quite "fat" for a 7mm pen. I like making a pen with some material on it. Even though I paint the tubes or blank, I find the Designer quite forgiving. Here's one that I just made with an Evergreen blank and gold finish. It's fatter than it is supposed to be, but I like it. It was sold for $35. Again, this somewhat underwhelming, but for an hours work and $8 in materials, I can buy more kits and blanks that I am likely to never use LOL.