My first time, I got 4 week old chicks and used a collapsible puppy playpen as a brooder, pine shavings , a Brinsea heater, a chick nipple waterer, and a galvanized feeding ring. Was plenty large enough to house 4 chicks- (could’ve done 6 easily). I put a small perch in the pen and they learned early. This system worked great and was easy to transition to their big coop/water/feeding etc.
My BIG mistake as a new chicken keeper was keeping the brooder inside an unused bedroom in the house- the dust is TERRIBLE- next time it will be outside in the garage!!
Good luck- it’s a lot of fun!