We have a box brooder that goes in the corner of the hen house. It has sliding doors to adjust as needed for heat/air circulation and runs on a thermostat. When they outgrow that they have their own partition in the house. After the season is over, we sometimes put them in the greenhouse, first in the box and then right on the ground. They love that, and it seems like they feather out faster outside.
Once though, when we didn't have all that stuff, I'd ordered too many chicks (imagine!) to fit in a tub or box, and we were having a bad cold snap with ice, so put down newspapers, then ran lawn edging around the legs of my old chrome dinette table, filled it with shavings and hung a light under it for a few days. It worked great and the kids ALWAYS remember that - peeps under kitchen table!