This is a photo of the reflection of my camera (obviously.) The mirror was plastic, so there was a lot of distortion. I did a 4 second delay at ISO 50. It took 7-8 shots, but it came out nicely.
The fun trick was to get the camera to focus on the right spot. I used a rubber chicken (!) to trip the camera to focus on a reflective point. After that, it was pretty easy. The lens attached is a 52mm polarizer, so that should have acted as an ND4 filter.