Okay, now I owe y'all a picture, but I finally did it and the answer is: Beautiful brushed metal, at least on mine, with the white plastic mouthpiece plug essentially flush into the end of the metal cartomizer pipe. I don't know what metal it is (steel? aluminum? cadmium?) but it looks as good as a stainless battery. I peeled one that was developing an extra-annoying lift at the seam... the adhesive is extremely gooey, but a lot of patience with olive oil and a paper towel will get it clean, I'll try the freezer trick next time.
ATTN: Kanger - You're shooting yourselves in the foot by not offering them like this! Not only does it look a lot better (no more weird extra tape-width-thickness on the carto vs. the battery), it 'feels' better - no more flaps of tape, no more struggling to figure out how to hold it to reach the battery button 'ergonomically' without the tape seam scratching my lips... Labeling would be an issue, but just stamp them or put a tape ring down away from the mouth end.