What other things can i use other than a light to keep my chickens warm?

[OVERxCAST]

I cant buy a heat pad right now. What other things can i use to keep my baby chicken warm?

 

[itgns]

Um, I'm using a mild space heater. I got the thermometer and made sure it could maintain the proper temperatures with all the settings in the right place, first though.
I haven't really heard much on whether it's good or bad since most people just opt for lights, though.