We built this brooder box last summer from scrap lumber we had about and a new roll of hardware cloth. Happy to say that this year we had a broody hen raise 7 chicks to about 3 weeks old (then they were sold) and had zero issues from snakes! That is a huge win for me!
https://sourwoodhill.com/2019/07/14/the-building-of-a-brooder-box/
https://sourwoodhill.com/2019/07/14/the-building-of-a-brooder-box/