I built the brush pen. Click the title for link to the original,Clay Butler, article on the parts necessary. I made quite a mess with the initial ink filling. I figured out the cartridge has a plunger that allows you to draw ink in without the mess.
Anyway, I love the thing. It's like having a windsor newton that you never have to re-moisten.
I posted some examples of my inking. It has smudges and a lot of rust apparent in my inking ability. Plus I was never much of an inker. But you can see how fine the line can be.
The little page of mechanisms are thumbnail sizes. All these sketches fit on paper 5 by 8.
http://www.lamy.com/content/products/accessories/refills_and_inks/index_eng.html
The link above takes you to the only hard to track down part. The Lamy cartridge. You want the Z26 Lamy converter
