I saw in comments where some guy talked about extending the life of his Staedtler Mars Graphic Duo 2000 brush pen ("The brush pen with more names than any other") by removing the plain tip with a pliers and somehow switching the ink supplies. He gave no details so I wasn't sure how that would work. But I pulled of the plain tip end (the pens have a plain tip on one end and a brush tip on the other) with pliers and, indeed, it had a little foam ink supply, fat and juicy with ink.
The brush tip end pulled off easily as well, and it was bone dry of course since that's mainly all I use. It's a simple matter then to switch the foam stick things. And re-insert the tips. It worked brilliantly, the brush tip was instantly back in fine fettle. What a boon this will be to humanity (or at least cartoonists.)
ps. Chris Garrison (who writes/draws "Our Heroes" on dummcomics.com) put me onto these great pens, that you can't buy in your local art store, for the most part, at least if you live where I do.