I'm currently using a medium sized dog crate for 12 2week old chicks and a duck. I cut pieces of cardboard to line the sides so they couldn't squeeze through the bars, I punched some holes in the cardboard and zip tied it to the bars. Someone is giving me an unused dogs whelping pen that I'll move them to when they outgrow the crate. I'll probably put the second brooder in the coop around 5 weeks with a heat lamp. Use what you have on hand.....check craigslist for cheap ones. You can also split them into 2 groups if you only have smaller boxes/crates/tubs to work with. Speaking of tubs, somebody on here used an unused bathroom tub for a brooder.
