Wait until you see my setup. It is a bucket with a false bottom for a mash tun and a 12 gallon copper pot from the side of the road in Mexico (not cheap because of the copper). You could substitute that pot for an aluminum one if you want to and do the exact same thing as I do to make 15 gallon batches (after boiling at least one full vessel worth of water to create a passive oxidization layer to prevent the aluminum from entering your beer). That is literally all I use, along with a few other 5 gallon pots for moving liquid around manually and putting the beer into for chilling in my pond water. Super stone age stuff and you can make great beer doing it that way. I know some Aussies are doing no-chill and I'm sure they do fine too. I want my hops to stop cooking when I say so personally, but that doesn't mean you can't pull it off. If you have say, a 6.5 gallon boil vessel you can pull of 10 gallons of some styles right now by using top off water and adding some sugars after the boil (stouts, Belgians, honey beers, etc).