Oyster shell Christmas tree? I'm intrigued! It sounds like you're using a unique and natural material to create a festive decoration. The first step is to gather enough oyster shells to create the shape of a tree. You can use a mixture of small and large shells for a more interesting look. Then, you'll need to glue them together in the shape of a tree. Once the glue dries, you can decorate it with lights or other festive decorations. What do you think? Do you have all the supplies you need?