I once used a big rubbermaid tool box. I covered my with window screen too, and that was great. Just a tip, if you use window screen, take a small piece and try to light it to make sure it isn't flammable or meltable. You don't want to have a baby chick fire in your living room. I would say that a rubbermaid tub is about the best on-the-fly brooder you can have. Nice part is you can easily clean it and re-use it for something else when you're done if you want to. I have one that i use to transport chickens, instead of a cat carrier. I cut a hole out of the lid and attached window screen. Then when i need to take a chicken somewhere, i have a ready made way to carry them around.
