people heating mats V plant heating mats

i have a half baked idea I wonder if could be used in some way. There are chicken people that make "cookie tin heaters" to keep water from freezing in the winter. Basic idea is to install a light bulb in a cookie tin and set it under the chickens water. Would the same principle, a light inside "something". under the seed trays work? The size of the container and the size of the lights combined to make the right heat. Maybe the string of Christmas lights in something with a larger surface area would be a good combination?

A metal folding table with a lamp under it should do about the same, just don't let the bulb get too close to the table. I once had a small dog that i put in a wire kennel in living room at night, I set flats on top of the kennel and covered it all with a blanket at night, letting the dog's body heat keep the flats warm, during the day, the heat of the room kept it warm.
Ed

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"Agriculture is our wisest pursuit, because it will in the end contribute most to real wealth, good morals, and happiness."
Thomas Jefferson to George Washington 1787