Bowl brewing

I’ve heard a lot about bowl brewing recently and would like to try it, but alas, my teaware seems to be against me.

Despite having quite a lot of teaware in my cupboard, I don’t have anything that could be called a tea bowl. I have teapots from 80 ml to 150 ml, several cups from 100 ml to 220 ml, and 355 ml mugs, plus a 500 ml teapot, but nothing bowl-shaped that could brew tea. Could any of these vessels work, or will I have to buy something else (and if so, how large)? Some of my 180 ml cups kind of look like bowls, but I have no idea what amount of tea to put in them. My searches for chawans usually turn up containers from 350 to 500 ml.

Any advice about this tea-brewing method would be appreciated.