I am building a device that needs to be inside of a microwave oven but somehow needs to communicate with another device outside of the microwave.

What materials can I use to reflect microwaves so they don't come into contact with the electronics in the device?

The frequency of the microwaves in a microwave oven is pretty much the same frequency that is used in bluetooth. I was thinking the really only possible way of doing this is to have an antenna that is small enough that it can slip outside of a microwave oven through the door (but small enough so the door is still able to close properly).

What materials could I use to protect the electronics of the device from microwaves? Is there a way to have this device communicate with another device outside of the microwave oven without the microwaves interfering with it?