I was speaking to David's8 on Saturday and mentioned a repair I did on the Rover fuel tank using a product called Q-Bond.
My tank had a tiny leak and had tried the usual two pack putty method of repairing it but the hole was so small the putty would go into the hole and seal the leak. I was speaking to a body shop and he recommended Q-Bond so I bought a pack and removed the tank applied the product and for the past 6 months have had no leaking tank. It can be used on plastics, metals and is a great product to keep handy on the garage shelf. Highly recommended