So rather than spend $80+ on an “electric hen” I just made one myself for about $15. Basically, it’s a heat mat (facing down) built into a sloped stand creating this little pocket of heat so chicks can get in under it to get warm. Just like they do with a mama hen.
Added a bit of cardboard over the top because their birds, they will poop on it. And replacing that bit of cardboard is easier than cleaning the heat mat.