I know I found this idea somewhere on the internet, but upon searching again I'm unable to find the link. If this was your idea and you want to claim it, let me know, I want to give credit where it's due.
I've built several of these "kid warmers" since our first kidding season. They're made of recycled plastic 55-gallon drums. Our local farm supply keeps a good stock of them. The ones I pick out are food-grade, usually holding soy sauce or bbq sauce it it's former life. They come washed out but I like to wash em out a little further. They are simple to construct, just use a jigsaw to cut a door opening and an opening for the can light. There is some simple wiring to be done on the can light and you need to be sure to fasten the warmer to something sturdy, we just tie them to the wall. Goats see anything elevated as a challenge to their climbing skills! I use a 125 watt heat bulb which is safely recessed in the can light and a little straw in the bottom for a nice cozy retreat from the cold.
In the video are 5 of our most recent arrivals, 2 doelings and 3 bucklings. In related news our crop from last year is maturing and turning out very nice. We have some goats for sale on our Southwest Missouri Boer Goat site, please take a look around. We're quite proud of the quality goats we've raised! Pictured here is one of the doelings for sale, Harmony Hill Lotus.