bunnyjadwiga

For absorbant layers, hemp is golden but cheap cotton flannel works. I think I use about 8 layers of flannel. I cut up old nighties so it's threadbare, but if you get new flannel you can probably use less.

I have used felted wool for backing, and polar fleece. With fleece you have to make sure you have the repelling side the right way.

I think PUL is the most common backing, though.

http://www.celticclothswholesale.com/ has supplies.