If you are looking for an alternative on how you can bond together two separate sheets of metal, then you should try using a vhb tape instead. A vhb tape is a double-sided strong adhesive tape which can be used to bond two items together. Sheets of metal can be bonded together without any bumps from rivets or bolts. This can create a flat surface on the metal which is ideal for aesthetic purposes. There is also a vhb tape that is specially created to be used underwater which can be ideally used in boats and swimming pools.