Easier said than done
The idea is easy to think of, but when it was time to put it down on paper it was a very difficult task accomplish. The reason being, metal is used in ovens to help heat, but if a metal plate is used in a microwave environment with exposure to microwaves, the metal intercepts the heating waves and decreases heating efficiency of the object, while sparks are produced within the enclosure. On the other hand, in an oven environment, materials best suited for microwave heating are weak heat conductors and inefficient for oven use. The problem lay in the need to find a suitable material that worked well in both environments.
