Especially the silverpoint pen. I've been smearing it all over paper and using an eraser to pull the light back out.
Silver point is a piece of silver wire.
I've inserted it into a clutch pen. It will only draw on a surface which has been treated with something like gesso or gauche. The old masters used it. You tend to get incredibly thin delicate lines as well as an odd ethereal quality. It's hard to get darks, but overtime the silver tarnishes and turns brown.