I'm getting my brooder ready (it's never too early, right?) and I plan to use a big cardboard box. It's heavy-duty cardboard and is about 3'w x 3'l x 18" deep. I figure this will work for a couple weeks until my 6 chicks get too big for it. My big concern is if I need to worry about a chick getting crushed by the other chicks into a corner. Has anyone had this problem? Should I round out the corners to prevent this? As long as the heat lamp is in the middle and I monitor the temp carefully I'm hoping the box will work. Otherwise I have a giant Rubbermaid tub and a large dog kennel to use. Both have slightly rounded corners. Thanks!