hehe, I just got my stencils from Ernie (good guy) working.....before I used something much tougher like thick vinyl. I say that to make the point that, he's not kidding when he says hold the pad on the stencil for 3 second intervals at a time or you'll burn them up quick. Also, the q-tip method seems easier at first, but it's really not in the long run. Make or buy a pad of some sort and you'll be happier in the long run.
I actually use 2 9 volt batteries with wires and alligator clips. Etching solution from USAknifemaker seems to work better than salt water. For my etching pad, since I've got plenty of file scraps hanging around from making file knives, I took the handle end and left about a half inch of the flat portion for the pad. I clip one of the alligator leads to the handle and rap a piece of old t-shirt around the flat to make a pad. It works really well so far.
I say all this as a newish knifemaker who has been trying to keep everything in budget. Yes, I can now say that spending money on the stuff, and/or going to the trouble of using plans like mentioned above is so much better in the long run and if you're seriously going to be doing this for a while.