My beautiful set of Tibetan Tea Pots and a ??

I inherited these from my grandfather about 25 years after his passing. I know they were very precious and special to him. He kept them in a locked display case. All I know about them is they are from Tibet. He visited there and purchased these sometime in the late 1930's-early 1940's. I would LOVE to know what the third container is. It is like a puzzle. We have tried to open it, to no avail. You can twist, turn, pull, etc and it will not open nor will it completely fit back together. I am wondering if it is a ritualistic vessel or offering vessel of some kind. Any information would be very appreciated. I would also like to know about how old they are. There are no markings on them nor any kind of a signature anywhere. Also, the metal appears to be hand hammered and the decoration on them is coral and turquoise. On the medium tea pot, the are two Buddhas on each side. I have found (1) tea pot on eBay that is like #2 of mine, except the coral and turquoise are opposite, a pair of Foo dogs that match and a trinket box, all are matching in style and design. There was no history on any of those items either. PLEASE help me find out about these beautiful pieces of history. (I apologize for the sideways pictures).
Many thanks-
Keri Neuling