@JKJ: I make my own ferrules, too, but having been given a LV gift card, I bought one of the Hosaluk ferrules from LV. The hole drilled in the handle is only 1/4" larger than the diameter of the tool shaft.
I really like the Jimmy Clewes cam locks, too. The one advantage of the Hosaluk ferrule is that the tool can be inserted through the ferrule as far as I like. I have a Oneway gouge is that is really long - too long for my taste. With the ferrule, I cans shorten the gouge to any length I want. The cam locks are closed ended, so that is not possible.