Also, for 7mm Euros, the length of the centerband that fits on the tenon may vary between brand and plating on the pen. I think most are the same, but CSUSA Rhodium is longer for sure.
As far as material, I'm not sure what you have in mind. I set my calipers to ~ 0.200 and use the points on the ID tangs to scratch a mark on the pen blank. Like Dario, I take the tenon down with a parting tool and try to undercut the blank a tiny bit to make sure the centerband doesn't have a gap between the back of the CB and the end of the barrel when it is glued in place.
NOTE: I do use the PSI sizing sleeve / bushing tool, but it's OD does not match the CSUSA centerbands.
I know, more than you asked...