One tip I found while doing several similar ones is in the sanding phase. Since you do not have a bead or other type of angled cut dividing the CB from the pen if the pen is even the slightest bit off center then when you twist it you r fingers with find a ridge along one edge of the CB. When you are down to 400 grit stop the lathe, loosen the nut, turn the CB 1/4 turn then retighten and sand. Repeat this through a full cycle of rotations. This should fix any concentric alignment issues. great pen by the way.