I tried using plastic 5 gallon paint containers/pails on my CT-22 - but one after another they crumpled (along with my ego). They must be using something a little stronger in their design. I am currently using a small steel trashcan that makes a 'pop' when the unit is fired up. It has not crumpled yet - but I have a few other things to try when it does.
One suggestion I received (and my next to try) was to glue two 5 gallon pails together, one inside the other. That might work. If the bottom is strong enough cut off the bottom of the outer pail to reduce the height. I also have a builders tube to cut up and try but that needs a bottom on it as well as a top.
SteveD