|Diving suit - 1882|
This is just screaming out to be used as some kind of magical mcguffin. It could easily be built along the lines of the Apparatus of Kwalish (AD&D DMG p.137) or something like that.
It need not necessarily be intended for use under water, just because the original was — it might be designed to keep an interplanar traveller safe in the extreme environments to be found in many of the other planes of existence. Alternately, it could be used as a steampunk or VSF space-suit.
Whatever you do with it — it's just too cool :)