R-A7 (Sandcrawler Droid)
This custom was very quick and easy. I simply removed the black paint from the POTF2 Death Star Droid, and underneath the black was this great silver finish. A highly reflective surface can be hard to get a picture of, so my scan doesn't really do the figure justice.
To remove the paint, I used square cotton swabs dipped in fingernail polish remover. For a few hard-to-reach spots, I used Q-tips.
I'd heard that some people who tried this custom used too much fingernail polish remover, and the silver finish also came off the figure. It's difficult to explain how much to use, but start off with just a few drops and try it out. Increase the amount until you feel you're able to rub off the paint in a few wipes. If you're leaving any fingernail polish remover on the figure as you wipe, you're using too much.
You'll notice that there are some places where I've left a little black paint in the cracks. I did this on purpose to give the droid a slightly worn look, and it also brings out the details of the mold a little more. Of course, to be true to the scene in A New Hope where this droid appears, you could also add some weathering by drybrusing on some brown. I liked the glossy finish, so I decided against the weathering.