Yeah, I assumed it would be a long shot. I also agree that the refresh flash for something like a clock would be pretty bad, I was thinking that you rarely stare at the mirror information for that long. That also means that using a more power hungry solution with PIR would likely be fine (as long as standby power is low).

Thanks for the reply :)

So I’m planning to build a Magic Mirror shortly and am considering using either a spare RPi B I have lying around, or perhaps a cheap Fire tablet. If I were to use the RPi, I was wondering whether it would be possible to use an e ink display, with the contrast inverted to have a black background. Would this work through 3mm acrylic? My main worry is the brightness would be too low…