Yes mate i know that. I am asking what material people use to make their own?
Like Pharaoh said, I've never really heard of anyone making them. I get my 7x16 bags from filterbag.com for less than $4.00 each, so it would be hard to imagine it being at all cost-effective. In your situation you could make something out of aquarium filter pads like these: http://www.petsolutions.com/C/Floss-Foam-Aquarium-Filter-Media/I/Filter-Felt.aspx