#1) The Churchill is a very, very nice pen but you need to be careful with the nib coupler. When you press the nib coupler into your blank at assembly, DO NOT let it get turned at an angle whatsoever. This pen has a reputation for breaking right inside the brass tube, where the plastic coupler is inserted, and most think it is because of a hairline fracture that happens when pressing together.
As far as closed-end methods, here is how I do the ones where I don't have the nice mandrel from Arizona Silhouette (I have the mandrel for the Baron but nothing else, but it is good).
My "mandrel" is a modified pin-chuck made out of brass. Aluminum would work as well.
Using a beall collet chuck with a 5/8" collet, I put in a ~4 inch long piece of 5/8 diameter brass or aluminum rod (from any local metal distributor).
I mount the metal in the collet chuck and tighten it down, put lathe on a higher speed (2000rpm+).
Using the brass tube for the pen you want to make, mark how long you need the mandrel be to fit inside the brass tube (ie, all the way).
I use an old bowl gouge with a really aggressive grind on it to do the shaping, and it cuts pretty impressively (not a clean cut, but who cares). Cut away the brass (and wear eye glasses PLEASE!) carefully and mill the length you need down to the inside diameter of the tube. You can use digital calipers but it isn't necessary.
When you get ***almost*** there, you can use heavy-grit sandpaper (like a belt-sander belt, 80 grit) to "sneak up" on a tight fit.
Your goal is to have the mandrel fit inside the brass tube very, very tightly, but not tight that you have to pound the blank onto it.
Quick Tip: If you accidentally turn the brass too small (which is inevitable), you can use CA glue to "beef it back up" to size. My mandrels are a bit worn out, so I usually lay on a layer of thick CA and spray with accelerator. After it cures hard (one min) I put the blank on and go to work.
The ONLY TWO tricky parts to closed-end pens is the nib end (use calipers to get the right diameter) and the closed-end (you will get chatter, possibly, from the tool as you cut).
Once you make your first one, you will be hooked. Have fun!