No, it is not possible to make a conventional microwave oven transparent. The walls of a microwave oven are typically made of metal, which is opaque to microwave radiation. The metal walls contain and reflect the microwaves inside the oven, allowing them to heat the food while preventing the microwaves from escaping and causing potential harm.
The metal used in microwave ovens, usually steel or stainless steel, has a high conductivity that effectively reflects and contains the microwave radiation. If the walls were made transparent, the microwaves would escape, rendering the oven ineffective at heating food.
However, it is worth noting that there are specialized microwave systems used in research or industrial settings that employ materials such as quartz windows to allow observation or interaction with microwave radiation while maintaining containment. These systems are designed for specific purposes and are not typical household microwave ovens.