make your own mandrel- i actually meant bushes. but i hear what you are saying though Brian.
with the hassles of kits (quality and compatibility between batches), cartridges that may or may not fit, bushes, mandrels and such like, i am planning to mainly make kitless when I use up my current kits. If you have to spend £7+ to get something reasonable, i would rather spend that on a nib and feed. It does limit the possibilities for wooden pens though.