the outer decorative part of a microwave is typically made of plastic materials. More specifically, it is often made from a type of plastic known as "acrylonitrile butadiene styrene" (ABS). ABS is a common thermoplastic that is known for its impact resistance, durability, and ability to be molded into various shapes and designs, making it suitable for use in household appliances like microwaves.
However, please note that the materials used in consumer products can vary over time due to advancements in technology and changes in manufacturing processes. To get the most up-to-date information on the specific materials used in a particular microwave model, it is best to refer to the product documentation or consult the manufacturer directly.