That's what tumblers do. It only works if both A and B contribute the same sum, of course, and that means if you have 93 million dollars to tumble, you need oth

That's what tumblers do. It only works if both A and B contribute the same sum, of course, and that means if you have 93 million dollars to tumble, you need other people to contribute another 93 million. Which no one will, on such a short notice. Thus you end up owning both A and B, in which case the mixing is useless.