Can't use a spray release product as it would get places where I want the urethane to stick. I used silicone grease on the mold for the transmission mount I fixed. Just about anything would work as a release agent, even motor oil for this project. The urethane may not even stick to the plastic rings, but I don't want to take that chance, because I need to reuse them for the other side. I know it will peel right off the plastic mixing cups I've used for the urethane. I'll probably use a plastic sheet on the bottom.
