I have a small batch of chicks that I keep in a brooder. i made them a small pillow and filled it about 1/3 full with rice. i placed it a little bit less then half way under the light of the heat lamp. the warmth from the light heats the rice and keeps the pillow warm. they really seem to like it. it's almost like a nest for them. they snuggle right in. you can also put it in the microwave for about a min. i also put a clean towel on it every day so they arent sleeping in poo.
Neat idea. I was thinking about doing something like that to bring home my chicks from a shared order.