I would add a USB Microphone
https://www.amazon.com/Kinobo-Microphone-Desktop-Recognition-Software/dp/B00IR8R7WQ/
And a PIR Sensor
https://www.amazon.com/PIR-motion-sensor-HC-SR501-Arduino/dp/B00L9GKN3I/
If I was to do it again, I would call your local glass shops first. I got the same acrylic mirror from Amazon and no matter how careful I was with the frame, it flexes and create a funhouse mirror effect. I called around and the first glass shop I contacted had glass two-way mirror for roughly the same price.
What are you planning to do with the acrylic cement?