Bocc ... if you like metal, look for a titanium tank. I don't know if I've seen a "slim" titanium but if you find it the titanium can torch to a gorgeous purple. Stainless can get sort of iridescent purple but to get it you have to go so hot that it can overtorch the steel. Titanium purple can be amazing.
I have a Cobra (the "real" cobra, not the chinese rip), which has a titanium cap, that I used my wife's jewelry torch on. I'll try and get a good picture of the color tomorrow. It isn't perfect because I didn't want to overdo it with the torch but it will give you an idea of the purple color. It is by far my favorite atomizer for looks (with a cobalt blue tank) but too big for a smaller pipe.
I bought a used kiln recently for controlled "torching" to get more exact colors but I don't have a 220v socket for it so will be a bit before I can get it set up. However if I do get it going I'll be happy to do some coloring for people if the temp control is still accurate. If the control is accurate I'll be able to oxidize titanium and stainless both to their prettiest ... though I like the randomness of the torch (vs. kiln) on some things. Of course, I've also ruined a piece of stainless with the torch, too, as I didn't realize how thin the tube on my telescope mod was. But titanium handles it better.