None of the links in this thread seem to work.
I would imagine that any of the tumbler manufacturers would have drums available as accessories or replacement parts.
I have two tumblers and they have nice, heavy rubber drums. But the lids are also a combination of rubber and metal and they are a tight fit into the drums so that the water or other liquid would not leak out. They also have an external aluminum cap which is held in place by a central screw-on knob. This cap has an outer edge that is tapered so it helps to hold the drum's rim tight against the cover. Four pieces all together: rubber-metal cap with a central stud, aluminum cap, an aluminum washer, and a screw-on knob. The tops are a bit difficult to remove but, so far there are no leaks. And the drums are so thick that I would guess it will take a century of use to wear them out. Sorry, in spite of how well made these drums are, I can't mention the brand name here. But I would recommend them. PM me, I guess.