I interpret this to be a challenge. Build a modified slim with centerband and do not use a saw to make the centerband as well do not use a barrel trimmer. Everyone should have a drive spurr, so there should be no problem there. A collet chuck is going to be the most convenient, but Butch does not have or does not use one..therefore it's a perfect opportunity to build your own jam chuck. You spin a cone similar to the taper. You drill out the inside, you make a couple cuts in the end like an x. The blank goes in the hole once it is round and you pound it home, the cuts will squeeze into the headstock holding the blank in place like a collet and the tailstock comes up to keep it from popping out. Although for some of us, this is very basic stuff, it's amazing what you can learn from actually doing it. It is good to think of different ways of approaching something because it expands the mind which will allow you to think of new ideas using this system that couldn't be done otherwise. Or..maybe your chop saw broke and now you can't make a pen? Yes you can. If you don't have a drill chuck, I'm sure Butch would say use a drill press because there is no other way, but other than that, make an entire slim and centerband without cutting the centerband with a saw. By doing so, the barrel trimmer will not be needed either.
Here is mine. I had to make a couple of these for a customer, so fortunately I had the inlay on top already set. Because I did not use any saws of any kind <the inlay of course does not count as it's an add on and has nothing to do with constructing the pen from blocks of wood>, It took longer but I was able to nail the center of the lizard dead square and my centerbands always look good, but by doing them on the lathe they are flawless all the way around. By cutting them on a chopsaw and then drilling with a drill press, sometimes the centerband looks perfect but if you measure it might be off by a millimeter as you go around the pen and the eye might not see it..this all happens because the drill bit might wander off just a hair while drilling causing the tube to not be perfectly square to the blank. So it was a bit of a pain not using any saw to make my pen, but the end result is an improvement and the added time was probably worth it. It only took me 2 hrs to make this pen by using the lathe only, and some of that time was spent carving the footprints. I used a 7mm euro kit because I can't give the customer a flat top and slim clip, but otherwise it's the same thing. Started it before work, finished it when I got home.