Cluster ornaments, also known as tree toppers or finials, are a decorative element that is placed at the top of a Christmas tree. They can be made from a variety of materials such as glass, metal, and plastic and can come in many different shapes and sizes. Some popular styles include angels, stars, and snowflakes. To cluster ornaments, start by grouping several smaller ornaments together and then placing them on top of the tree. You can also use wire or thread to attach the ornaments to each other to create a more cohesive look.