I just purchased these kits myself so I haven't tried them yet, but you might also want to consider the RAW pen kits which come in fountain pen varieties. They come in raw base metals such as stainless steel, brass, and even aluminum which of course is very light. They utilize the Majestic Squire bushings and only use one tube, so depending on how you turn it I believe you can come up with a smaller profile than the traditional two tube capped rollerball/fountain pen kits. The drawback (which to me is actually a big plus) is there are no embellishments whatsoever on this kit - it definitely looks different than the other kits out there.