Mini ITX builds are fun, and a nice challenge to get good hardware into them - I have a Thermaltake Core V1 Arctic case, and in it I've managed to squeeze a Zotac RTX2080Ti Twin, a Ryzen 3900X and an NZXT Kraken X42 140mm AIO in push pull config.
It's not pretty in there, not by a long shot, but it's small, and quick, and surprisingly quiet.