I’ll start by saying that I’m not a fancy equipment guy.
The latest issue of Zymurgy has an ad on the back cover for a 1-gallon unitank. Complete with a tri-clamp dump port on the bottom and a schematic showing that its 6 1/4" in diameter. No price info and I’m afraid to look it up. I just don’t get it.
That may be true for some, but for me it’s strictly that the batch size matches my consumption. If a piece of gear is out there that meets my needs at an acceptable price point, I have no problems spending the money for it, even though I’m not brewing 5+ gallon batches.
That being said, this almost sounds like it would be most useful for something like a saurgut bioreactor or a small scale yeast brink rather than brewing 1 gallon batches of beer. This may be better suited for a small nanobrewery than homebrewers.