[Douglas_OW]

I thought that I would try to push this up to the active threads now. If anyone is interested in making a heating mat like this, you will be able to get Christmas lights very cheaply soon. I paid less than $1.00 for mine, when they were on clearance. Buy one set for the mat, and another just for the spare bulbs.
Or you can just not use any heating mat at all; that seems to be the consensus of the knowledgable folks here.

This is the heating mat that I made from some scrap lumber and Christmas lights. The frame is made of 1x3's and the top is pegboard. I use it in the basement where the temperature it is a steady low sixties F. If I think it is running too warm, I just loosen a couple of the bulbs. It does speed up the germination of tomato seeds and is very useful for peppers, too. Here are some pictures: