Hmmm. How about this. Put several jars, warmer than 33, in a three-sided square. Put a heavy towel over the top to form a cave the chicks can get inside. The towel should hang down around the jars to insulate them and hold the warmth in, to keep them warm longer. I'm thinking two or three jars on two sides and one or two on the end. Should be nice and cozy in there!