i've always been a fan of sharpies. you can open one up, pull out the ink cartirage, take a baggie with pot in it and roll it, and slide it in there. then just put the plastic part with the tip back on (just snaps in and out) and you have not only a working sharpie, but also a sharpie full of herb
you can fit more than enough in there, but not too too much, that way if they tell you (for whatever reason) to get rid of it, it wouldn't be THAT big of a loss. i just say im using it to get autographs, and it works.
along those same lines, i've been looking to make a stealth pipe for a long time. so i ahve this metal pen, which comes apart with a little effort. i pushed a screen in the non-writing end, under the metal cap that i made removable, and it's now a pipe. i pack a bowl, put the butt-end cap on, put the regular cap on and go. and i glued a smaller ink cartirage in there, so it still writes.
oh, yeah.