As far as I know, Carlo's acrylics guy is Caesar, who also built displays for Club Reef.
How big were you thinking? Does it need to look good? ( I like my stuff to look good, even when it's not usually seen, but I'm picky). How much were you wanting to spend? My 8-ish gallon ATO container cost about a $100.
If looks don't matter much. And there's flexibility on size/space you can go the repurposing route and save a lot of money.
You can make your own, but it's not as easy as some people might think. I have never seen a YouTube video on making your own tanks that really shows the best practices of strongly chemically welding acrylic, just the easiest fastest ways. Having stuff precut by a supplier and then just butting it all together and "gluing" ( solvent welding ) it together is somewhat undesirable because usually the precut material will not have the edges ready to go, they'll need prep, and generally you make the pieces slightly oversize, welding them together with excess edges that later get flush routed off. I used to make acrylic casework for art museums-- I have made some of my own aquarium stuff, but I've also paid a pro to do it a couple of times, to save me the time.