Commercial brooders are expensive and often don't give great access or visuals of the chicks to enable easy monitoring or even just to watch for fun.
Therefore, I designed a brooder out of a bird cage/rabbit cage multi-story which can be divided into 4 different compartments if required to brood chicks at different ages or just to spread them out as they get older and bigger.
The above video gives a run through of a cage brooder setup from lighting to flooring.