I bought a set about 4 years ago from a guy on ebay who used to make them but I can't find him now I guess he stopped. I remember that his were advertised as being made from closed cell neoprene foam though so I hope that helps you if you decide to make them yourself. 4 years on the gaskets are still leak proof so it is definitely a good material for the job. Maybe you could make some yourself and sell them on I bet they would sell as nobody else seems to be making them now.