Just completed a few coats for my Fex. Damn large surfaces! Found that it's much better to basecoat with Dheneb Stone before you use Bleached Bone.
I have magnetised all the spare arms using the tips found at Miniwargaming.com. You can just google "magnetising carnifex" and that should give you some results. I bought like 1000 rare earth magnets and shared half with my cousin (Joasht).