Ok, so we took apart the microwave. We got an exact replica of the motor we were thinking of, and also a fan to help with ventilation. As we were taking it apart, I remembered my original idea when my mom told me to make an automatic door: Simply connect it to the latch of the door. It will be much, much simpler. It turns on(for 15 minutes, not 30) and pulls the latch, and the door swings open.