For barrel trimming I have one of the usual pen mill sets that cover 4 or 5 different sizes. Pop this in the battery drill and trim away. However I have had a few pens where the pen mill set doesn't have the barrel size. The Zeta is one example. I have got away with this by wrapping a number of layers or parcel tape around the next size down trimmer bit. One of the other methods or barrel trimming is to use a sander, either belt or disk. I don't have one, but what I do have is a Proedge sharpener which is a similar thing. Would this be done thing to use or sacrilege. I would use an old or dedicated spare belt.
One thought comes to mind about using the belt/disk sander is the problem that the blank might not be quite square in the first place.
